High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
vt: stabilize tty reference in kbd_keycode with tty_port_tty_get
kbd_keycode() reads vc->port.tty without acquiring a tty reference,
racing against con_shutdown() which clears port.tty under a different
lock. Use tty_port_tty_get()/tty_kref_put() to hold a proper reference
for the duration the tty pointer is needed.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
ipvs: clear IPv4 options after rebasing tunnel ICMP errors
ip_vs_in_icmp() rebases an skb from the outer ICMP packet to the
quoted original request before passing it to icmp_send(). However,
IPCB(skb)->opt still describes the outer IPv4 header.
A timestamp option in the outer header can therefore leave an offset
that points into the quoted transport header after the rebase.
__ip_options_echo() treats a byte at that stale location as the option
length and copies it into the fixed-size option storage on the
__icmp_send() stack, causing a stack out-of-bounds write.
Clear the stale option metadata after resetting the network header.
Keep the remaining control block fields, including the ingress
interface used by the ICMP response path.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
packet: use consistent hard_header_len in TX_RING send path
tpacket_snd() reads dev->hard_header_len independently for skb
allocation and header construction in tpacket_fill_skb(). Concurrent
netdevice reconfiguration can therefore make the reserved headroom
smaller than the amount later pushed, or make copylen - hard_header_len
negative.
Snapshot hard_header_len once before processing ring frames and use it
for the frame limit, headroom allocation, copy length, and skb
construction. Pass the snapshot to tpacket_fill_skb().
The separate SOCK_DGRAM consistency problem between hard_header_len and
header_ops->create is not addressed here.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
net/packet: reset the MAC header on the packet-socket transmit path
packet_parse_headers() resets the MAC header only for a SOCK_RAW frame
whose socket did not bind a protocol. A protocol-bound SOCK_RAW socket,
any SOCK_DGRAM frame, and the legacy SOCK_PACKET path therefore leave
skb->mac_header unset here.
For frames sent via __dev_queue_xmit() this is harmless: it resets the
MAC header unconditionally. But the packet-socket PACKET_QDISC_BYPASS
path uses dev_direct_xmit(), which does not, so the frame reaches
ndo_start_xmit() with the MAC header unset. A driver that reads
eth_hdr(skb) on transmit then dereferences skb->head + (u16)~0, an
out-of-bounds access ~64 KiB past the head -- the same class fixed for
one consumer in commit f5089008f90c ("macsec: do not read an unset MAC
header in macsec_encrypt()").
packet_parse_headers() runs only on the transmit path, where skb->data
points at the start of the L2 header for every packet-socket type
regardless of its length: SOCK_RAW and SOCK_PACKET carry a user-supplied
header and SOCK_DGRAM has one built by dev_hard_header(). Reset the MAC
header unconditionally, mirroring __dev_queue_xmit(), so the frame is
anchored on the bypass path too.
Found by 0sec (https://0sec.ai) using automated source analysis;
verified against source and matched to the macsec KASAN report in
f5089008f90c. Compile-tested.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
packet: synchronize pressure clearing with ring reconfiguration
packet_set_ring() updates the RX ring state under sk_receive_queue.lock,
but used to publish the tpacket receive mode through po->prot_hook.func
after releasing that lock. packet_poll() and packet_recvmsg() can then
run the pressure clearing path after the ring has been cleared while
still seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference
stale or NULL ring storage.
Move the existing receive hook assignment into the same
sk_receive_queue.lock section as the ring state update. Keep the
assignment otherwise unchanged, including on TX ring reconfiguration, to
avoid adding behavior changes that are not required for the fix.
Serialize packet_recvmsg() pressure clearing with the same queue lock
only after PACKET_SOCK_PRESSURE has been observed. If the flag is clear
and the socket has moved away from tpacket_rcv, packet_set_ring() has
already detached the socket and waited for synchronize_net(), so no new
packet input can set the flag again.
packet_poll() already holds sk_receive_queue.lock, so it uses the new
unlocked helper directly.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
net/sched: reject overly deep qdisc hierarchies
Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
walkers and exhaust the kernel stack. The existing loop check does not
cover the create-and-graft path, so a hierarchy can still be extended by
creating a new child qdisc below an already deep parent.
Store the hierarchy depth in struct Qdisc and update it when qdiscs are
grafted. Reject new child qdiscs once the parent is already at the maximum
allowed depth.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
inet: frags: publish queues before arming timer
inet_frag_create() arms the fragment queue timer before inserting the
queue into the fqdir rhashtable. If the namespace fragment timeout is
zero or negative, the timer can run before the queue is published.
The timer callback then marks the queue complete, tries to remove a node
that is not in the hash table yet, and drops the anticipated hash
reference. Creation can subsequently publish the completed queue without
restoring that reference, leaving a stale hash node after the caller drops
the remaining reference.
Publish the queue first and arm the timer while holding the queue lock.
This makes timer expiry wait until the queue is visible in the hash table,
so inet_frag_kill() can remove the node and balance the hash reference.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ebt_nflog: pin the NFLOG backend
nf_log_unregister() runs after the per-net teardown so its final RCU
grace period also drains readers that obtained the logger from a per-net
binding. However, ebt_nflog passes an explicit ULOG log type to
nf_log_packet() without holding a reference on the selected logger module,
unlike the xt_NFLOG and nft_log frontends.
An ebtables nflog rule can therefore remain callable while nfnetlink_log
is unloaded. The resulting interleaving is:
CPU 0 CPU 1
nfnetlink_log_fini()
unregister_pernet_subsys()
kfree(nfnl_log_pernet(net))
ebt_nflog_tg()
nf_log_packet()
nfulnl_log_packet()
instance_lookup_get_rcu()
The global ULOG logger is still registered at this point, so CPU 1
dereferences the per-net state after CPU 0 has freed it. KASAN reported:
BUG: KASAN: slab-use-after-free in instance_lookup_get_rcu
Read of size 8 at addr ff110001052e6210 by task poc/92
Call Trace:
instance_lookup_get_rcu+0x1ce/0x1f0 [nfnetlink_log]
nfulnl_log_packet+0x248/0x2fb0 [nfnetlink_log]
nf_log_packet+0x204/0x300
ebt_nflog_tg+0x351/0x550
ebt_do_table+0xedf/0x22b0
Allocated by task 90:
__kmalloc_noprof+0x186/0x470
ops_init+0x6d/0x420
register_pernet_operations+0x2f6/0x670
register_pernet_subsys+0x23/0x40
Freed by task 93:
kfree+0x131/0x3c0
ops_undo_list+0x3e3/0x700
unregister_pernet_operations+0x232/0x490
unregister_pernet_subsys+0x1c/0x30
nfnetlink_log_fini+0x34/0x450 [nfnetlink_log]
Acquire the ULOG logger module reference when an ebt_nflog rule is
validated and release it when the rule is destroyed. Request the NFLOG
backend for legacy callers when needed, matching xt_NFLOG. This prevents
module teardown until all ebt_nflog rules have stopped using the logger.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
ipv4: fix use-after-free in fib_nhc_update_mtu()
fib_nhc_update_mtu() walks the nexthop exception table under RTNL, but
RTNL does not serialize this walk with PMTU exception updates. The walk
uses rcu_dereference_protected() with a constant true condition without
holding fnhe_lock.
The following interleaving can therefore occur:
CPU 0 CPU 1
fib_nhc_update_mtu() update_or_create_fnhe()
load fnhe spin_lock_bh(&fnhe_lock)
fnhe_remove_oldest()
unlink fnhe
kfree_rcu(fnhe, rcu)
<quiescent state>
access fnhe after grace period
KASAN reported:
BUG: KASAN: slab-use-after-free in fib_nhc_update_mtu+0x3df/0x410
Read of size 8 at addr ffff888107d49000 by task poc/90
Call Trace:
fib_nhc_update_mtu+0x3df/0x410
fib_sync_mtu+0x7a/0xd0
fib_netdev_event+0x229/0x3f0
netif_set_mtu_ext+0x33a/0x570
dev_set_mtu+0x88/0x120
The same walk updates fnhe_pmtu and fnhe_mtu_locked. These fields form a
pair and other writers serialize them with fnhe_lock. RCU alone prevents
reclamation, but would still allow concurrent writers to leave a mixed
pair.
Walk the table under RCU and acquire fnhe_lock only while updating each
exception. RCU keeps the current entry alive while the short critical
section serializes its paired PMTU fields. This avoids holding the global
lock while scanning all 2048 buckets for every nexthop.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.1
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix OOB read in rtw_get_wpa_ie()
rtw_get_wpa_ie() reads bytes at fixed offsets into a vendor-specific
information element without checking that the element is long enough,
causing an out-of-bounds read for a short trailing IE.
The function locates a vendor-specific IE (EID 221) with rtw_get_ie()
and then compares a 4-byte OUI+type at pbuf + 2 and reads a 2-byte
version word at pbuf + 6. Those accesses require the IE body to be at
least 6 bytes, but rtw_get_ie() only guarantees that the element fits
within the buffer; it does not enforce a minimum body length. A
vendor-specific IE whose length byte is 0 to 5, placed at the end of
the buffer, therefore makes these reads run past the end of the IE and
past the end of the buffer itself.
The buffer holds information elements taken from received management
frames and from the IE blob passed to rtw_cfg80211_set_wpa_ie(), which
is kmemdup'd to its exact length, so the read can run off the end of
the allocation.
The sibling helpers rtw_get_sec_ie(), rtw_get_wapi_ie() and
rtw_get_wps_ie() in this file already reject too-short vendor-specific
IEs before their OUI memcmp(); rtw_get_wpa_ie() was never brought in
line with them, and needs a minimum of 6 rather than 4 bytes because
of the version word. Add the missing length check.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.8
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix missing shared-key auth challenge length check
The WEP shared-key authentication handler uses the challenge-text
element's attacker-controlled length without checking it against the
fixed 128-byte chg_txt buffer.
In OnAuthClient() the length from rtw_get_ie() - up to 255 - is used
to perform memcpy() into the 128-byte pmlmeinfo->chg_txt, so a
malicious AP sending a malformed WLAN_EID_CHALLENGE element can
overflow/underfill chg_txt by up to 127 bytes. It is reachable over the
air, before association, during shared-key authentication. In the case
of an overflow, the driver can write out of bounds. In the case of an
underfill, the driver can echo stale buffer memory.
The challenge text is defined to be exactly 128 octets, which is
already provided as the WLAN_AUTH_CHALLENGE_LEN define; require the
element to be exactly that length before use.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: validate monitor transmit frame lengths
rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
then reads the 802.11 frame control field without checking that a base
802.11 header remains.
The data path also pulls the calculated 802.11, QoS and SNAP header
span before confirming that the skb contains it. A truncated frame can
therefore cause out-of-bounds reads or leave insufficient data for the
Ethernet address writes.
Reject frames that do not contain the base 802.11 header and data
frames that do not contain their complete calculated header span.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
ALSA: usx2y: bound the hwdep mmap fault offset
snd_us428ctls_vm_fault() turns the faulting page offset into a kernel
address with no bound of any kind:
offset = vmf->pgoff << PAGE_SHIFT;
vaddr = (char *)(...)->us428ctls_sharedmem + offset;
page = virt_to_page(vaddr);
get_page(page);
vmf->page = page;
return 0;
snd_us428ctls_mmap() checks only the length of the mapping, never the
offset, and us428ctls_sharedmem is a single page from
alloc_pages_exact(). For a character device file_mmap_size_max()
returns ULONG_MAX, so the mm layer imposes no ceiling either. Every page
offset above zero resolves to a struct page outside the object, and the
handler installs it into the caller's address space read-write; the vma
is not marked read-only.
The caller picks the page frame with a single mmap() argument and gets
read-write access to a page of kernel memory it does not own; an offset
that lands in an unpopulated vmemmap region oopses instead.
A process that can open the hwdep node of an attached US-X2Y reaches
this after loading the FPGA image through the same node; no capability
check is involved.
On 7.2.0-rc5 (arm64), mmap() with a large offset:
Unable to handle kernel paging request at virtual address fffffdffc45d5ac8
pc : snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
Call trace:
snd_us428ctls_vm_fault+0x68/0x140 [snd_usb_usx2y]
__do_fault
__handle_mm_fault
handle_mm_fault
el0_da
Reject any offset outside the shared region. The pcm hwdep handler in
usx2yhwdeppcm.c computes its address the same way and needs the same
bound.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
ALSA: FCP: fix OOB write in fcp_meter_ctl_get()
fcp_ioctl_set_meter_map() bounds the user-supplied Level Meter map size
by the driver's own limit of 255
if (map.map_size < 1 || map.map_size > 255 ||
map.meter_slots < 1 || map.meter_slots > 255)
return -EINVAL;
and passes it to fcp_add_new_ctl() as the control's channel count, where
it is stored as elem->channels.
Every control read writes into struct snd_ctl_elem_value, whose integer
array is declared long value[128], so the limit is 128, not 255.
fcp_meter_ctl_get() stores one 64-bit word per channel into that array
with no bound of its own:
for (i = 0; i < elem->channels; i++) {
int idx = private->meter_level_map[i];
int value = idx < 0 ? 0 : le32_to_cpu(resp[idx]);
ucontrol->value.integer.value[i] = value;
}
snd_ctl_elem_read_user() serves that object from
memdup_user(_control, sizeof(*control)), 1224 bytes on LP64 out of
kmalloc-2048. offsetof(struct snd_ctl_elem_value, value) is 72, so
element i is written at byte 72 + 8 * i and element 144 already lands
past the allocation. At map_size 255 the last store ends at byte 2112,
888 bytes past the object and 64 bytes into the adjacent slab object.
The stored words come from the device and meter_level_map[] selects
which word lands in which slot, so extent and contents are both
controlled.
The core does not catch this. snd_ctl_check_elem_info() is reached only
from __snd_ctl_elem_info(), which snd_ctl_elem_read() calls under
CONFIG_SND_CTL_DEBUG; without that option snd_ctl_skip_validation() is a
compile-time true. __snd_ctl_add_replace() validates kcontrol->count and
never inspects elem->channels.
Installing an oversized map needs CAP_SYS_RAWIO, but the control outlives
the hwdep descriptor that created it, so the out-of-bounds stores are
issued by any process able to read controls on /dev/snd/controlC0.
KASAN on 7.2.0-rc5 (arm64), triggered by an unprivileged control read:
BUG: KASAN: slab-out-of-bounds in fcp_meter_ctl_get
Write of size 8 at addr ffff000017af04c8 by task fcp_trigger/185
__asan_store8
fcp_meter_ctl_get
snd_ctl_elem_read
snd_ctl_ioctl
Allocated by task 185:
memdup_user
snd_ctl_ioctl
The buggy address is located 0 bytes to the right of
allocated 1224-byte region [ffff000017af0000, ffff000017af04c8)
Bound the map size by the ABI limit rather than by 255, and bound the
store loop at the sink so it cannot run past the value array whatever
elem->channels holds.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
perf/core: Fix group leader use-after-free after sibling detach
perf_group_detach() handles leader and sibling detach differently. When the
group leader is detached, all siblings are promoted to singleton events and
their group_leader pointer is reset to themselves. When a sibling is
detached, it is removed from the leader's sibling_list, but its
group_leader pointer is left pointing at the old leader.
That is harmless when the sibling is being closed and freed immediately, as
in the DETACH_DEAD path. It is not safe when the sibling is detached but
kept alive, such as during CPU hotplug with DETACH_GROUP. In that case the
sibling is removed from the context, while its file descriptor can still
keep it alive.
A typical failing sequence is:
- A group contains leader L and sibling S.
- CPU hot-unplug detaches S with DETACH_GROUP, removing it from
L->sibling_list but leaving S->group_leader == L.
- L is later closed and freed.
- A PERF_IOC_FLAG_GROUP ioctl on S follows S->group_leader and
dereferences the freed leader.
This was reproduced by running the perf event fuzzer, CPU hotplug, and a
stress workload concurrently:
Unable to handle kernel paging request at virtual address 006b6b6b6b6b6cdb
CPU: 2 PID: 12489 Comm: perf_fuzzer 6.18.7 PREEMPT
pc : perf_ioctl+0x34c/0xc68
x20: ffffff89a3fa2c70 x8 : 6b6b6b6b6b6b6b6b
Code: 943c4a0e 340047a0 f9404a94 f9411e88 (f940b908)
Call trace:
perf_ioctl+0x34c/0xc68 (P)
__arm64_sys_ioctl+0xa0/0xf4
invoke_syscall+0x58/0xe4
el0_svc_common+0xa8/0xdc
do_el0_svc+0x1c/0x28
el0_svc+0x40/0xc0
el0t_64_sync_handler+0x68/0xdc
el0t_64_sync+0x1c4/0x1c8
The fault happened in perf_ioctl(), where perf_event_for_each() follows
the stale group_leader pointer and perf_event_for_each_child() then
dereferences the freed leader's context.
Fix the use-after-free by promoting the detached sibling to a singleton.
Also fix __event_disable() cgroup accounting and event state change.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
fbdev: bitblit: bound-check glyph index in bit_cursor()
bit_cursor() fetches the glyph under the cursor with
c = scr_readw(vc_pos);
src = vc_font.data + ((c & charmask) * w * height);
where charmask is 0x1ff when vc_hi_font_mask is set. The screen buffer
value comes directly from scr_readw() and may be larger than the current
font's glyph count.
Syzkaller triggers this via vcs_write(). The Call Trace shows
vcs_write() in vc_screen.c writing an arbitrary 16-bit value with
writev() to /dev/vcsa, which vcs_write_buf() in vc_screen.c stores via
vcs_scr_writew() without checking charcount. The stored value is later
read in bit_cursor() in bitblit.c.
When the font is changed from a font with 512 glyphs to a font with
256 glyphs, the screen buffer can retain characters with the high
bit set from the previous mode, which could also produce the same
out-of-bounds access.
BUG: KASAN: global-out-of-bounds in soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
Read of size 16 at addr ffff800086c57970
Call Trace:
soft_cursor+0x378/0x6bc drivers/video/fbdev/core/softcursor.c:70
bit_cursor+0xa90/0x1108 drivers/video/fbdev/core/bitblit.c:365
fbcon_cursor+0x344/0x498 drivers/video/fbdev/core/fbcon.c:1427
hide_cursor+0xdc/0x2d0 drivers/tty/vt/vt.c:883
update_region+0x100/0x18c drivers/tty/vt/vt.c:669
vcs_write+0x8ec/0xaf0 drivers/tty/vt/vc_screen.c:685
bit_putcs_aligned() and bit_putcs_unaligned() already clamp the glyph
index to vc_font.charcount. Apply the same clamp in bit_cursor() after
extracting the attribute and masking, before indexing fontdata.
The fix completes the bounds checking started in commit 18c4ef4e765a
("fbdev: bitblit: bound-check glyph index in bit_putcs*"), which missed
the cursor path.
This change should be safe because the clamp reuses the existing
contract from fbcon: charcount is maintained under console_lock in
con_font_set() and fbcon_font_set(), and hi_font_mask is cleared when
switching from 512 to 256 glyphs. When stale screen data with high bits
remains after a font switch, or when vcs_write() stores an arbitrary
value, clamping the index to 0 prevents the out-of-bounds read without
changing cursor semantics — the same fallback bit_putcs uses.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
mm/huge_memory: fix huge_zero_pfn race
Patch series "mm/huge_memory: fix huge_zero_pfn race", v2.
There is a subtle race in the reference-counted huge_zero_folio
implementation.
The fast path atomic logic fails to account for the fact that the shrinker
(which drops the final huge_zero_refcount pin) can overwrite huge_zero_pfn
with the ~0UL sentinel value in shrink_huge_zero_folio_scan() after a
racing get_huge_zero_folio() installed a valid value there.
This results in huge_zero_folio being correctly set but huge_zero_pfn
being set incorrectly and thus is_huge_zero_pfn() and consequently
is_huge_zero_pmd() will misidentify the huge zero folio as being an
ordinary THP folio.
This can result in the huge zero folio being split and otherwise treated
incorrectly.
The solution to this is very subtle as there is an atomic fast path, and
thus ordering in weakly ordered architectures has to be treated very
carefully.
The first commit fixes the issue by introducing a spinlock around
huge_zero_[pfn, folio, refcount] write, with careful consideration paid to
load/store ordering in the fast path. It is placed first and kept as
small as possible so that it can be backported on its own.
The second commit is a pure cleanup which reworks the
CONFIG_PERSISTENT_HUGE_ZERO_FOLIO logic to better separate the persistent
logic from the dynamically allocated one.
This patch (of 2):
If !CONFIG_PERSISTENT_HUGE_ZERO_FOLIO, the huge_zero_folio is refcounted
by huge_zero_refcount and returned by mm_get_huge_zero_folio().
When the caller is done with the huge zero page, its reference count is
decremented. Only a shrinker can set the reference count to zero.
A race can unfortunately occur between a shrinker decrementing the
reference count to zero and a concurrent page fault.
This is because shrink_huge_zero_folio_scan() might, if very unlucky, be
preempted between setting huge_zero_refcount to zero and writing an
invalid value.
During this time get_huge_zero_folio() could write to huge_zero_pfn before
shrink_huge_zero_folio_scan() resumes.
In this event the huge zero folio will be persistently misidentified
causing the THP code path to be entered inappropriately for the huge zero
folio:
CPU 0 CPU 1
=======================================|=================================
shrink_huge_zero_folio_scan() |
atomic_cmpxchg() sets refcount to 0 |
xchg() sets huge_zero_folio to NULL | get_huge_zero_folio()
| | atomic_inc_not_zero() -> zero
preempted for a long time | Allocate new huge zero folio
| | Write valid huge_zero_folio
v | Write valid huge_zero_pfn
Overwrite huge_zero_pfn with ~0UL <--- Invalid overwrite!
This results in is_huge_zero_pfn() and is_huge_zero_pmd() incorrectly
returning false for a huge zero page which could result in issues like the
huge zero folio being incorrectly split.
Note that the issue is with huge_zero_pfn not huge_zero_folio, as
get_huge_zero_folio() uses cmpxchg() gated on huge_zero_folio being NULL
with a retry loop and shrink_huge_zero_folio_scan() uses xchg() to set
huge_zero_folio.
Fix the issue by introducing a spinlock, huge_zero_lock, to prevent
concurrent write of huge_zero_folio, huge_zero_pfn and huge_zero_refcount.
There needs to be significant care taken here to ensure correctness:
The fast path in get_huge_zero_folio() uses atomic_inc_not_zero(), which
is outside of the critical section, and means huge zero allocation is
gated on zero huge_zero_refcount.
The fast path doesn't use huge_zero_lock, so the critical section is
irrelevant to it.
So invariants are required - huge_zero_refcount MUST:
* Only be set in the huge_zero_lock critical section to ensure
serialisation of huge_zero_pfn, huge_zero_folio and
---truncated---
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.4
In the Linux kernel, the following vulnerability has been resolved:
net: smc: fix splice entry lifetime imbalance in smc_rx_splice
smc_rx_splice() passes pages to splice_to_pipe() before taking the
references that cover the lifetime of each splice entry. In the
VM-backed RMB path, splice_to_pipe() may drop unqueued entries through
smc_rx_spd_release(), while queued entries are released later via the
pipe buffer callback.
The old post-splice accounting also derives the number of queued VM pages
from an offset mutated while building the descriptor, and a multi-page
splice pairs one sock_hold() with multiple sock_put() calls.
Take the page and socket references for every candidate entry before
splice_to_pipe(), and drop the matching private state, page reference,
and socket reference from smc_rx_spd_release() for entries that never
get queued. This fixes a refcount imbalance that can underflow page
refcounts and trigger a use-after-free.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent in6_dev_get() from resurrecting inet6_dev
in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally
increments its refcount. Device teardown can clear the pointer and drop
the last reference between these operations. The increment then
resurrects an object whose RCU free has already been queued, so callers
can use it after it is freed.
Use refcount_inc_not_zero() and return NULL when the object has already
reached zero. RCU keeps the memory accessible through the attempted
reference acquisition, and a successful increment pins the object for
the caller.
An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3)
kernel reproduced the invalid reference acquisition as UID 1000:
refcount_t: addition on 0; use-after-free.
ip6_mc_source+0xef4/0x17e0
It was followed by the corresponding reference underflow in
ip6_mc_source(). The supplied trace from the same unpatched revision
additionally shows the access after the RCU read-side section ends:
BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0
Write of size 8 at addr ffff888015b50240 by task poc/1219
Bug found and triaged by OpenAI Security Research and
validated by Trail of Bits.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.8
In the Linux kernel, the following vulnerability has been resolved:
net/dibs: Correct freeing of dmb_clientid_arr
A dibs device interrupt handler can be active after dibs_dev_del() and
may still access dmb_clientid_arr. (UAF)
In case of a failure in dibs_dev_add() being called by dibs_lo_dev_probe()
dmb_clientid_arr is freed twice (double free).
Free dmb_clientid_arr in dibs_dev_release() after last reference is gone.
Note that allocating in dibs_dev_add() instead of dibs_dev_alloc() is ok
for now, because no dmbs can be registered before dibs_dev_add().
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.5
In the Linux kernel, the following vulnerability has been resolved:
NTB: ntb_netdev: Preserve RX queue depth on allocation failure
ntb_netdev_rx_handler() hands the received skb to the network stack
before allocating its replacement. If the allocation fails, nothing is
reposted. Every failure therefore takes one buffer out of the RX queue
while the interface remains up, and enough failures eventually stall
reception.
A retry path could refill the queue later, but ntb_netdev has none.
Allocate the replacement first instead. If that fails, drop the packet
and repost the same skb. This keeps the queue full and lets packet
delivery resume as soon as memory is available again.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.5
In the Linux kernel, the following vulnerability has been resolved:
netfilter: bridge: release template ct on non-IP path
A bridge nftables ct zone set rule can attach a conntrack template to
an skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6
EtherTypes, nf_ct_bridge_pre() currently overwrites skb->_nfct with
IP_CT_UNTRACKED without releasing the existing template reference.
That makes the per-cpu template, and any temporary templates allocated
for concurrent use, unreachable and leaks memory until the host runs out
of slab.
Reset the skb conntrack state before marking the frame untracked so the
existing template reference is dropped on the non-IP path.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.5
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack: defer invalid log until after unlock
TCP and SCTP conntrack paths can emit invalid-packet logs while ct->lock
is still held.
When invalid logging is routed to nfnetlink_log and conntrack export is
enabled, the log path can re-enter conntrack netlink glue and dump the
same conntrack again. Protocol attribute dumping may take ct->lock, so
logging while holding that lock can deadlock.
Defer the TCP invalid logs by storing only the minimal log context while
ct->lock is held and emitting the log after unlocking. Also make the TCP
timeout-lowering invalid path return whether a log is needed, then emit
that log after unlocking.
Do the same for the SCTP invalid state-transition log that can be reached
while ct->lock is held.
Add a lockdep assertion to nf_ct_l4proto_log_invalid() so future callers
that log invalid conntracks while holding ct->lock are caught outside TCP
and SCTP as well.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.5
In the Linux kernel, the following vulnerability has been resolved:
net/sched: act_ct: fix sk_buff leak when the header checks reject a packet
tcf_ct_handle_fragments() runs its header sanity checks before handing
anything to the defragmentation engine:
if (family == NFPROTO_IPV4)
err = tcf_ct_ipv4_is_fragment(skb, &frag);
else
err = tcf_ct_ipv6_is_fragment(skb, &frag);
if (err || !frag)
return err;
tcf_ct_ipv4_is_fragment() returns -EINVAL or -ENOMEM;
tcf_ct_ipv6_is_fragment() adds -EPROTO when ipv6_find_hdr() fails. None of
them frees or queues the skb, so on that path the caller still owns it.
tcf_ct_act() however funnels every non-zero return into the
ownership-transfer exit:
err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag);
if (err)
goto out_frag;
...
out_frag:
if (err != -EINPROGRESS)
tcf_action_inc_drop_qstats(&c->common);
return TC_ACT_CONSUMED;
TC_ACT_CONSUMED means the action took ownership of the skb, so no caller
frees it - sch_handle_ingress(), sch_handle_egress() and
tcf_qevent_handle() all deliberately skip the free for that verdict. The
skb is therefore orphaned: one sk_buff plus its data buffer is leaked per
malformed packet, unbounded. Note the drop counter is already incremented
for these errors, so the statistics claim a drop that never happens.
Three different ownership states reach out_frag: today - the skb may be
queued by the defrag engine (-EINPROGRESS), already freed by
nf_ct_handle_fragments(), or still owned by us. Tell the caller which of
those it is, and free the packet ourselves in the last case, which
restores the TC_ACT_SHOT behaviour that predated the Fixes: commit.
Reproduced on v7.2-rc6 with a 54-byte frame carrying a 40-byte IPv6
header with nexthdr = 0 (hop-by-hop) and nothing after it, on a
clsact ingress chain with "action ct". kmemleak reports one leaked
232-byte skbuff_head_cache object plus its 704-byte data buffer per
packet; with this patch it reports none.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
dibs: initialise dibs->lock in dibs_dev_alloc()
dibs->lock is initialised by dibs_dev_add(), but a dibs device can
already take interrupts before that call: ism_probe() runs
ism_dev_init(), and hence request_irq(), before it calls
dibs_dev_add(). No client can have registered a dmb at that point, so
no dmb interrupt can occur, but a GID event interrupt can, and
ism_handle_irq() takes dibs->lock unconditionally on entry, before it
inspects anything else.
Initialise the lock in dibs_dev_alloc() instead, so that it is valid as
soon as a driver can publish the device to its interrupt handler.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
xdp: reject clones that overrun skb_shared_info tailroom
xdpf_clone() clones broadcast copies into a single page and sets
frame_sz to PAGE_SIZE. __xdp_build_skb_from_frame() later treats that
page like a normal XDP frame and expects the usual skb_shared_info
tailroom at the end of the buffer.
The current check only rejects frames whose linear xdp_frame header,
headroom, and packet data exceed PAGE_SIZE. A source frame backed by a
larger allocation can still satisfy that check while extending into the
clone's required shared-info area. When such a clone is converted back
into an skb, build_skb_around() places skb_shared_info over live packet
bytes and later writes can corrupt XDP return metadata.
Reject clones unless their linear area fits inside
SKB_WITH_OVERHEAD(PAGE_SIZE), matching the tailroom requirement already
enforced by the XDP-to-skb conversion path.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.8
In the Linux kernel, the following vulnerability has been resolved:
vxlan: do not arm the ageing timer on a device that is down
vxlan_changelink() arms vxlan->age_timer whenever the requested ageing
interval differs from the configured one:
if (conf.age_interval != vxlan->cfg.age_interval)
mod_timer(&vxlan->age_timer, jiffies);
There is no netif_running() test, so the timer is armed even on a device
that was never brought up. The only synchronous cancel in the driver is
the timer_delete_sync() in vxlan_stop(), which is .ndo_stop.
netif_close_many() drops devices without IFF_UP before
__dev_close_many() runs, so that cancel is skipped for such a device.
vxlan_setup() sets dev->needs_free_netdev = true and age_timer is a
member of struct vxlan_dev, so free_netdev() releases the allocation the
timer lives in while it is still queued on a timer_base.
expire_timers() unlinks the entry before it loads timer->function, so
the timer core writes through the freed object's list pointers:
BUG: KASAN: slab-use-after-free in __run_timers+0x208/0x654
Write of size 8 at addr ffff00001adace68 by task true/192
__asan_store8+0x84/0xac
__run_timers+0x208/0x654
run_timer_softirq+0x154/0x18c
Allocated by task 189:
alloc_netdev_mqs+0x64/0x720
rtnl_create_link+0x4ac/0x520
rtnl_newlink+0x758/0xd00
Freed by task 191:
netdev_release+0x40/0x58
netdev_run_todo+0x4a4/0x8c0
rtnl_dellink+0x200/0x4e8
The rtnl operations involved are netns-scoped, so an unprivileged user
can perform them in a new user and network namespace.
Arming the timer on a down device never had an effect: vxlan_cleanup()
returns early on !netif_running(), and vxlan_open() arms the timer for
any non-zero interval once the device is brought up. Add the missing
test.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.4
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: read virtqueues under worker locks
Commit bd50c5dc182b ("vsock/virtio: add support for device
suspend/resume") made the *_run flags transition from false to true when
restore installs replacement virtqueues. The RX, TX and event workers
read their virtqueue before locking and checking the corresponding flag,
so a worker delayed across freeze and restore can observe the replacement
queue's running state while retaining a pointer to the deleted queue.
Read each virtqueue under its mutex after checking the run flag, keeping
the pointer and state in the same queue generation.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
vsock/virtio: avoid refilling the RX queue after teardown
Commit b917507e5ad9 ("vsock/virtio: stop workers during the .remove()")
made the RX worker jump to its common exit when rx_run is clear. That
exit still refills the RX queue when the buffer count is low, so work
queued across virtio_vsock_vqs_del() can add buffers after the virtqueues
have been deleted.
BUG: KASAN: slab-use-after-free in virtqueue_add_sgs
Read of size 4 by task kworker/0:1
Workqueue: virtio_vsock virtio_transport_rx_work
Call Trace:
virtqueue_add_sgs (drivers/virtio/virtio_ring.c:2796)
virtio_vsock_rx_fill (net/vmw_vsock/virtio_transport.c:332)
virtio_transport_rx_work (net/vmw_vsock/virtio_transport.c:701)
process_one_work (kernel/workqueue.c:3314)
worker_thread (kernel/workqueue.c:3478)
kthread (kernel/kthread.c:436)
ret_from_fork (arch/x86/kernel/process.c:158)
ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
...
Freed by task 141:
kfree (mm/slub.c:6566)
vp_del_vq (drivers/virtio/virtio_pci_common.c:259)
vp_del_vqs (drivers/virtio/virtio_pci_common.c:285)
virtio_vsock_freeze (net/vmw_vsock/virtio_transport.c:912)
virtio_device_freeze (drivers/virtio/virtio.c:658)
virtio_pci_freeze (drivers/virtio/virtio_pci_common.c:601)
pci_pm_freeze (drivers/pci/pci-driver.c:1098)
device_suspend (drivers/base/power/main.c:1968)
Kernel panic - not syncing: KASAN: panic_on_warn set ...
Jump to a no-refill exit when rx_run is clear, leaving the normal exit
to replenish a running queue.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 10
In the Linux kernel, the following vulnerability has been resolved:
veth: fix skb length accounting after XDP frag adjustment
veth exposes non-linear skb fragments through an xdp_buff. If an XDP
program adjusts the fragment area, veth_xdp_rcv_skb() copies
xdp_frags_size back to skb->data_len but leaves skb->len containing the
old fragment contribution.
After a fragment shrink, this makes skb_headlen() larger than the actual
linear area. In the reproduced UDP receive path, __skb_datagram_iter()
copied 1024 bytes past the actual linear tail to userspace, starting at
struct skb_shared_info. The copied bytes included the affected skb's
nr_frags, xdp_frags_size, and a kernel pointer from
skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same
amount and truncated at the end.
Subtract the old data_len before replacing it and add the new data_len
afterwards, keeping skb->len and skb->data_len synchronized.
Additionally, bpf_xdp_pull_data() can advance data_end while leaving
frags present. The skb is then still non-linear, so the old
__skb_put(skb, off) triggers SKB_LINEAR_ASSERT().
Use skb_set_tail_pointer() and update skb->len explicitly instead,
following bpf_prog_run_generic_xdp(). Unlike __skb_put(),
skb_set_tail_pointer() does not require a linear skb.
A 60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by
1024 bytes from its fragment area. Before the fix, all 10 runs produced
corrupted payloads. After the fix, all 10 runs matched the expected
payload exactly. A forced-tailroom reproducer also exercises
bpf_xdp_pull_data() with frags still present; the old code triggers
SKB_LINEAR_ASSERT(), while this fix passes 10/10 runs.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
tipc: read le->link under the node lock in tipc_node_link_down()
tipc_node_link_down() caches the link pointer before taking n->lock:
struct tipc_link *l = le->link; /* unlocked */
if (!l)
return;
tipc_node_write_lock(n);
if (!tipc_link_is_establishing(l)) { /* deref l */
...
tipc_link_reset(l); /* write into l */
if (delete) {
kfree(l);
le->link = NULL;
The delete=true caller frees that very object under n->lock, so the lock
does not protect the cached pointer against it:
- CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link
supervision timer via tipc_node_timeout(), reads l unlocked and then
dereferences it under n->lock;
- CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable()
-> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true)
-> kfree(l).
The link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers
disable_media() only schedules the asynchronous cleanup_bearer() work, so
its synchronize_net() runs after the links are already gone. An in-flight
CPU A that has read l therefore dereferences freed memory once B frees it:
a use-after-free read in tipc_link_is_establishing(), and a use-after-free
write via tipc_link_reset() on the establishing branch.
The following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:
BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)
Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0
tipc_link_is_establishing (net/tipc/link.c:285)
tipc_node_link_down (net/tipc/node.c:1076)
tipc_node_timeout (net/tipc/node.c:843)
Allocated by task 9549:
tipc_link_create (net/tipc/link.c:490)
tipc_node_check_dest (net/tipc/node.c:1279)
tipc_disc_rcv (net/tipc/discover.c:252)
tipc_udp_recv (net/tipc/udp_media.c:389)
Freed by task 9549:
tipc_node_link_down (net/tipc/node.c:1084)
tipc_node_delete_links (net/tipc/node.c:1320)
bearer_disable (net/tipc/bearer.c:414)
__tipc_nl_bearer_disable (net/tipc/bearer.c:992)
Move the le->link read inside tipc_node_write_lock(), so it is serialised
against the kfree() in the delete path. A racing teardown now either has
not run yet, and we see a valid link, or has already run, and we see NULL.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
smb: client: Fix use-after-free in cifs_try_adding_channels()
cifs_try_adding_channels() takes a temporary reference to an interface
before dropping iface_lock. If cifs_ses_add_channel() fails, it drops
that reference and then increments iface->weight_fulfilled.
A concurrent interface list refresh can remove the list reference while
channel creation is in progress. In that case, the failure-path
kref_put() releases the last reference and frees iface. Updating
weight_fulfilled afterward then accesses freed memory.
Increment weight_fulfilled before dropping the temporary reference,
keeping iface alive for the final access.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.8
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Serialize accesses to the owner and mirror list with separate lock
Interaction between KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM and
KVM_CAP_VM_COPY_ENC_CONTEXT_FROM can cause two separate issues:
- in sev_migrate_from(), when the destination KVM is a mirror, the mirror
entry is moved from the source's list to the owner's mirror_vms list,
without holding the owner's lock unlike other writers of the owner's
mirror list (sev_vm_copy_enc_context_from(), sev_vm_destroy()).
A concurrent COPY or destroy can race with sev_migrate_from() and
corrupt the list.
- In sev_vm_destroy(), the *owner* is still active and could receive
concurrently a KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM that causes
sev->enc_context_owner to change. In this case the incorrect VM
receives kvm_put_kvm().
The second issue needs particular care because the owner could disappear
altogether (even though the race window is impossibly small) between
reading it and locking it. There is thus no way to perform the checks
under the owner lock without putting struct kvm under SLAB_TYPESAFE_BY_RCU
(which would allow kvm_get_kvm_safe() under RCU critical section).
It is much simpler to just use a global lock, since the critical
sections are so small and the new lock is always a leaf lock.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.4
In the Linux kernel, the following vulnerability has been resolved:
Revert "thermal/drivers/hwmon: Cleanup coding style a bit"
Revert commit 030a48b0f6ce ("thermal/drivers/hwmon: Cleanup coding style
a bit") that introduced a use-after-free into the error path of
thermal_add_hwmon_sysfs() by removing a valid check from it.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Use current_context for safe per-CPU buffer swap
The ring_buffer_swap_cpu() function currently checks the per-CPU
committing counter to determine if a buffer is actively being written to
before performing the swap. However, there exists a race window where
this check can be bypassed:
ring_buffer_lock_reserve
cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_a
rb_reserve_next_event
rb_start_commit // inc committing
if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) {...}
__rb_reserve_next
rb_move_tail
rb_end_commit(cpu_buffer); // dec committing => 0
/* interrupt hits here, successfully swaps! */
local_inc(&cpu_buffer->committing);
ring_buffer_unlock_commit
cpu_buffer = buffer->buffers[cpu]; // cpu_buffer_b
rb_commit
rb_end_commit
RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))
// triggers warning
The committing counter can temporarily drop to 0 during a single write
operation (within rb_move_tail), creating a window where swap can
succeed even though the write is still in progress. This leads to
inconsistent buffer state and triggers the RB_WARN_ON in rb_commit().
Replace the committing counter check with current_context checks, which
are set at the entry of ring_buffer_lock_reserve() and remain valid
throughout the entire write operation, providing a reliable indicator of
buffer busy state during swap.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.5
In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix Route Information option length validation
rt6_route_rcv() validates the Route Information option (RFC 4191) length
against the prefix length, but both checks are off by one.
rinfo->length is the ND option length in units of 8 octets and it
*includes* the 8-byte option header, so an option carrying N bytes of
prefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3
when Prefix Length is greater than 64, and 2 or 3 when it is greater
than 0. The code accepts length >= 2 and length >= 1 respectively.
ipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix,
so a Router Advertisement with (prefix_len=128, length=2) or
(prefix_len=64, length=1) makes the kernel read up to 8 bytes past the
end of the option. Those bytes end up in the prefix of the route that
gets installed, so they are visible to userspace:
# RA with a Route Information option (prefix_len=128, length=2)
# followed by a source link-layer address option, 01 01 de ad be ef ca fe
$ ip -6 route show
2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra
^^^^^^^^^^^^^^^^^^ the next option, read out of bounds
When the Route Information option is the last one in the packet, those
eight bytes come from the skb tail room instead.
Reject the option lengths RFC 4191 does not allow.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: clear skb2->cb[] in ip6ip6_err()
ip6ip6_err() clones an outer IPv6 ICMP error skb, pulls it to the
quoted inner IPv6 packet, and then passes the clone to icmpv6_send().
The clone still carries the outer packet's inet6_skb_parm in skb->cb.
If the outer packet had a Home Address Option, IP6CB(skb2)->dsthao
remains non-zero after skb_pull(). icmpv6_send() later calls
mip6_addr_swap(), which uses that stale dsthao offset against the quoted
inner packet. A malformed inner destination-options header can then make
the HAO lookup and address swap run past the end of the quoted packet
and corrupt skb_shared_info.
Clear skb2->cb[] before pulling the quoted inner IPv6 packet so the
reply path does not reuse metadata left by the outer IPv6 stack.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
fscrypt: use the mount idmap for the owner check in fscrypt_ioctl_set_policy()
fscrypt_ioctl_set_policy() calls inode_owner_or_capable() with
&nop_mnt_idmap before allowing an encryption policy to be set, instead
of the idmap of the mount the ioctl was issued on.
fscrypt is used by filesystems that support idmapped mounts (e.g. ext4,
f2fs), so on such a mount this compares the caller's fsuid against the
unmapped on-disk owner rather than the mapped owner: the actual owner
can be wrongly denied with -EACCES and an unrelated caller wrongly
allowed. Use file_mnt_idmap(filp) instead.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
sched/psi: Shut down rtpoll_timer in psi_cgroup_free()
psi_schedule_rtpoll_work() is called locklessly from the scheduler hotpath
and can race psi_trigger_destroy() taking down the last rtpoll trigger under
rtpoll_trigger_lock:
psi_schedule_rtpoll_work() psi_trigger_destroy()
rcu_read_lock();
task = rcu_dereference(rtpoll_task);
rcu_assign_pointer(rtpoll_task, NULL);
timer_delete(&rtpoll_timer);
mod_timer(&rtpoll_timer, ...);
rcu_read_unlock();
synchronize_rcu();
kthread_stop(task_to_destroy);
The group can then be freed with the re-armed timer still pending, and
poll_timer_fn() runs on freed memory.
461daba06bdc ("psi: eliminate kthread_worker from psi trigger scheduling
mechanism") deleted the timer synchronously after the synchronize_rcu(),
which prevented this but raced trigger creation instead: the deletion could
cancel the timer that a new trigger set armed during the grace period and,
as creation also reinitialized the timer at the time, corrupt it.
8f91efd870ea ("psi: Fix race between psi_trigger_create/destroy") moved the
initialization into group_init() and the deletion into the locked section,
trading the creation races for the window above.
Neither placement in the destruction path works. A pending timer firing
while the group is alive is harmless though. poll_timer_fn() just wakes the
rtpoll waitqueue and doesn't re-arm itself. Bind the timer to the group's
lifetime instead and shut it down in psi_cgroup_free(). Nothing can arm it
by then. timer_shutdown_sync() because the timer is never armed again.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.1
In the Linux kernel, the following vulnerability has been resolved:
ima: Instantiate file_truncate and path_truncate hooks
Instantiate the file_truncate and path_truncate LSM hooks to reset the
action cache flags (IMA_DONE_MASK) as soon as truncation is requested,
so the file, based on policy, is re-collected, re-measured, re-audited,
and re-appraised on next access.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions
The BPF verifier and the dynptr abstraction ensure that the memory space
referenced by a dynptr remains valid. They do not, however, provide any
guarantee that the contents of the memory are stable. kfuncs are
expected to remain memory-safe even if concurrent modifications occur.
bpf_get_fsverity_digest() didn't follow that: it could crash if
arg->digest_size was concurrently modified.
Fix that by using the known-good value hash_alg->digest_size instead.
Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return
type of __bpf_dynptr_size(). It doesn't appear that it can actually be
more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes
file-based pointers), but the correct type might as well be used.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 8.4
In the Linux kernel, the following vulnerability has been resolved:
bpf, sockmap: Fix sk_redir use-after-free in send verdict
sk_psock_msg_verdict() takes a socket reference for psock->sk_redir.
tcp_bpf_send_verdict() copies that pointer while holding the source socket
lock, but does not take a reference for the local copy before dropping the
lock around tcp_bpf_sendmsg_redir().
When apply_bytes keeps the cached verdict active, another sendmsg() on the
same source socket can consume the remaining bytes and release the cached
reference while the first thread still holds only the raw local pointer:
CPU 0 CPU 1
sk_redir = psock->sk_redir
apply_bytes remains nonzero
release_sock(sk)
lock_sock(sk)
apply_bytes reaches zero
psock->sk_redir = NULL
release_sock(sk)
tcp_bpf_sendmsg_redir(sk_redir)
sock_put(sk_redir)
tcp_bpf_sendmsg_redir(sk_redir)
The final sock_put() can free sk_redir before CPU 0 dereferences it.
KASAN reported:
BUG: KASAN: slab-use-after-free in tcp_bpf_sendmsg_redir+0xf39/0x1020
Read of size 8 at addr ffff888108537090 by task poc/87
Call Trace:
tcp_bpf_sendmsg_redir+0xf39/0x1020
tcp_bpf_sendmsg+0x977/0x1a50
__sys_sendto+0x32c/0x3a0
__x64_sys_sendto+0xdb/0x1b0
Allocated by task 85:
sk_prot_alloc+0x56/0x210
sk_clone+0x6f/0x14b0
inet_csk_clone_lock+0x24/0x740
tcp_create_openreq_child+0x25/0x2710
tcp_v4_syn_recv_sock+0x10a/0xe00
Freed by task 0:
__kasan_slab_free+0x43/0x70
slab_free_after_rcu_debug+0xa6/0x1e0
rcu_core+0x50a/0x1850
Last potentially related work creation:
__sk_destruct+0x3da/0x540
sk_psock_destroy+0x81e/0xab0
process_one_work+0x63a/0x1070
Take a temporary socket reference while the source socket lock still
protects psock->sk_redir, and drop it after tcp_bpf_sendmsg_redir()
returns. This keeps each unlocked use independent of cached-verdict
ownership.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
sctp: keep chunk->transport in step with the list it is queued on
__sctp_outq_flush_rtx() moves a gap-acked chunk onto another transport's
transmitted list without updating chunk->transport:
if (chunk->tsn_gap_acked) {
list_move_tail(&chunk->transmitted_list,
&transport->transmitted);
continue;
}
The chunk then sits on a live transport's list while chunk->transport still
names a different one. If that transport is removed - sctp_assoc_rm_peer()
from an ASCONF Delete-IP - sctp_transport_free() RCU-frees it and the chunk
is left with a dangling pointer. sctp_assoc_rm_peer() scrubs
peer->transmitted and asoc->outqueue.out_chunk_list, but the chunk is on
neither.
The pointer is not followed while tsn_gap_acked is set. A SACK that
reneges on the TSN clears the flag, and the next SACK reaches
tchunk->transport->flight_size -= sctp_data_size(tchunk);
inside the freed transport. KASAN reports a slab-use-after-free read in
sctp_check_transmitted(), freed from sctp_assoc_rm_peer(). Both the
removal and the SACKs come from the association peer.
Set chunk->transport at the move. The ordinary resend path needs nothing:
it reaches its list_move_tail() only after sctp_packet_append_chunk()
returned SCTP_XMIT_OK, and __sctp_packet_append_chunk() has rebound the
chunk by then.
Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
sctp: fix use-after-free of cached ASCONF chunk
addip_last_asconf caches the outstanding outbound ASCONF chunk. The normal
ASCONF-ACK completion path releases the chunk and clears the pointer.
However, sctp_asconf_queue_teardown() releases the cached chunk without
clearing addip_last_asconf. During peer restart handling,
sctp_sf_do_dupcook_a() queues SCTP_CMD_PURGE_ASCONF_QUEUE, which invokes
sctp_asconf_queue_teardown() while the association remains alive and leaves
the pointer dangling.
A delayed authenticated ASCONF-ACK can then reach sctp_sf_do_asconf_ack(),
which accesses the stale chunk and passes it to sctp_process_asconf_ack(),
causing a use-after-free and a second release.
Clearing the pointer exposes a race with T4 expiry. Peer restart handling
queues the timer stop before the purge, but SCTP_CMD_TIMER_STOP uses
timer_delete(), which does not wait for a callback already running on
another CPU. Such a callback can reach sctp_sf_t4_timer_expire() after
the purge and dereference NULL.
Clear addip_last_asconf after releasing the cached chunk, and make
sctp_sf_t4_timer_expire() consume a stale T4 expiry if no outstanding
ASCONF remains.
Published Aug 22, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
sctp: clear new_transport when removing a peer
sctp_process_asconf_param() stores a newly added peer transport in
asoc->new_transport. After all parameters in the ASCONF chunk have been
processed, sctp_sf_do_asconf() uses this pointer to send a HEARTBEAT to the
new transport.
An authenticated ASCONF from a remote SCTP peer can add a transport and
remove it again with a wildcard DEL-IP parameter in the same chunk. The
wildcard deletion preserves the transport on which the ASCONF arrived, but
removes the newly added transport through
sctp_assoc_del_nonprimary_peers(). The removal does not clear
asoc->new_transport, leaving it pointing to the removed transport.
sctp_sf_do_asconf() then creates a HEARTBEAT whose chunk->transport points
to the removed transport without holding a transport reference. During
local address replacement, src_out_of_asoc_ok keeps this HEARTBEAT on
control_chunk_list. After the transport is freed by RCU, a successful
ASCONF_ACK for the replacement address releases the queued HEARTBEAT and
sctp_outq_select_transport() reads the freed transport's state.
The issue was found during a static audit of SCTP objects. With an
authenticated peer, the reproducer triggered the same KASAN report in 2
of 2 unpatched runs on a KASAN-enabled netdev/main kernel:
BUG: KASAN: slab-use-after-free in sctp_outq_select_transport
Read of size 4 at addr ffff88800b9bd95c by task python3/197
Call Trace:
sctp_outq_select_transport+0x549/0x8b0 [sctp]
sctp_outq_flush+0x306/0x2c60 [sctp]
sctp_transport_immediate_rtx+0xaf/0x260 [sctp]
sctp_process_asconf_ack+0xa48/0xf70 [sctp]
Allocated by task 197:
sctp_transport_new+0x68/0x650 [sctp]
sctp_assoc_add_peer+0x258/0x12a0 [sctp]
sctp_process_asconf+0x5e9/0x1090 [sctp]
Last potentially related work creation:
__call_rcu_common.constprop.0+0x77/0xb70
sctp_assoc_del_nonprimary_peers+0x7c/0xd0 [sctp]
sctp_process_asconf+0xd9c/0x1090 [sctp]
The first invalid access was a four-byte read of transport->state at
net/sctp/outqueue.c:833. The same reproducer completed the full
authenticated ASCONF and local-address replacement sequence with this
change without a KASAN report or oops.
Clear new_transport when its peer is removed, before it can be used to
create the HEARTBEAT.
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.1
In the Linux kernel, the following vulnerability has been resolved:
RDMA/bnxt_re: zero shared page before exposing to userspace
bnxt_re_alloc_ucontext() allocates uctx->shpg via
__get_free_page(GFP_KERNEL). The buddy allocator does not zero pages
without __GFP_ZERO, so the page contains stale kernel data from
whatever object most recently freed it.
The page is then mapped into userspace via vm_insert_page() under
BNXT_RE_MMAP_SH_PAGE in bnxt_re_mmap(). The driver only ever writes
4 bytes (a u32 AVID) at offset BNXT_RE_AVID_OFFT (0x10) inside
bnxt_re_create_ah(); the remaining 4092 bytes of the page are exposed
to userspace unsanitised, leaking kernel memory contents.
Any user with access to /dev/infiniband/uverbsX on a host with a
bnxt_re device (typically rdma group membership) can read this data
via a single mmap() at pgoff 0 after IB_USER_VERBS_CMD_GET_CONTEXT.
Other shared pages in the same file already use get_zeroed_page()
correctly:
drivers/infiniband/hw/bnxt_re/ib_verbs.c
srq->uctx_srq_page = (void *)get_zeroed_page(GFP_KERNEL);
cq->uctx_cq_page = (void *)get_zeroed_page(GFP_KERNEL);
uctx->shpg is the only outlier. Bring it in line with the existing
convention by switching to get_zeroed_page().
Published Aug 22, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_route: fix fastmap use-after-free on filter
The route4 classifier maintains a 16-slot fastmap cache that stores raw
struct route4_filter pointers indexed by (id, iif). The reader
(route4_classify) populates this cache via route4_set_fastmap() for every
classified packet that hits a filter. The writer (route4_delete,
route4_change) clears the cache via route4_reset_fastmap() before
RCU-deferred kfree of the filter.
This creates a UAF race:
1. Reader walks the RCU-protected bucket chain, finds filter f
2. Writer unlinks f, calls route4_reset_fastmap(), then tcf_queue_work()
3. Reader calls route4_set_fastmap() and writes f into the cache
*after* the writer's reset, caching a pointer about to be freed
4. After the RCU grace period, kfree(f) executes
5. Next classified packet on the same (id, iif) tuple hits the stale
fastmap entry and reads f->res from freed memory
Reproduced with an mdelay(100) accelerator in route4_set_fastmap() and a
concurrent add/delete stress test (provided by both zdi and Santosh).
Both triggered KASAN slab-use-after-free reports in the route4 fastmap
paths.
Fix:
Introduce a per-filter boolean dying flag to suppress stale fastmap
republishing by in-flight readers.
Published Aug 21, 2026 · Updated Oct 16, 2026
High · CVSS 7.8
In the Linux kernel, the following vulnerability has been resolved:
packet: use consistent hard_header_len in non-ring send paths
packet_snd() reads dev->hard_header_len multiple times while allocating
and constructing an skb. Device reconfiguration can change this value
concurrently, for example through bonding device type changes.
For SOCK_RAW, packet_snd() can save a larger value in reserve and later
allocate headroom using a smaller value. Moving skb->data back by reserve
then places it before skb->head, and the following copy from userspace can
attempt an out-of-bounds write.
packet_sendmsg_spkt() has the same issue because it calculates its
reservation and header offset from separate reads before dropping the RCU
read lock to allocate the skb.
Add LL_RESERVED_SPACE_EX() for callers that already saved a header length.
Read hard_header_len once in packet_snd() and use it for allocation and
construction. In packet_sendmsg_spkt(), preserve the allocation-time value
through the device lookup retry.
The separate SOCK_DGRAM consistency problem between hard_header_len and
header_ops->create is not addressed here.
Published Aug 21, 2026 · Updated Oct 16, 2026
Critical · CVSS 9.8
In the Linux kernel, the following vulnerability has been resolved:
net: ipv6: clear suppressed fib6 rule result
fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(),
but leaves res->rt6 pointing at the released rt6_info.
If no later rule supplies a replacement, fib6_rule_lookup() still sees
res.rt6 and returns that stale dst to its caller. A suppressing rule can
therefore leak a released route back to rt6_lookup(), and the next put
hits rcuref_put_slowpath() from dst_release().
Clear res->rt6 when suppressing the route so suppressed lookups fall
through to the null dst instead of reusing the released one.
Published Aug 21, 2026 · Updated Oct 16, 2026
High · CVSS 8.8
In the Linux kernel, the following vulnerability has been resolved:
vhost: reset the vring metadata cache on vring reconfiguration
vq->meta_iotlb[] caches the vhost_iotlb_map that backs each vring
metadata region, and iotlb_access_ok() returns early on a cache hit,
taking the hit as proof that the region has already been validated:
if (vhost_vq_meta_fetch(vq, addr, len, type))
return true;
The cache is reset on VHOST_IOTLB_UPDATE and VHOST_IOTLB_INVALIDATE, on
device IOTLB (re)initialisation and on vq reset, but not when
VHOST_SET_VRING_ADDR replaces vq->desc, vq->avail and vq->used, nor when
VHOST_SET_VRING_NUM changes the region sizes.
With a device IOTLB attached both ioctls are accepted while the vq is
live, and neither validates the addresses at ioctl time: vq_access_ok()
and vq_log_used_access_ok() return true early because the addresses are
GIOVAs, deferring validation to prefetch time. Once the cache has been
populated that deferred validation no longer runs -- vq_meta_prefetch()
hits the stale entry and returns true -- and vhost_vq_meta_fetch() keeps
translating through the old mapping as
map->addr + addr - map->start
for an address the mapping no longer covers. vhost_copy_to_user() and
vhost_copy_from_user() consume the result with __copy_to_user() and
__copy_from_user(), which do not check it either, so a subsequent used
ring update or descriptor fetch accesses memory outside the region the
IOTLB actually maps.
Reset the metadata cache whenever the vring is reconfigured, so the new
addresses are pushed back through iotlb_access_ok()'s slow path.
Published Aug 21, 2026 · Updated Oct 16, 2026
