CVE-2022-49916: rose: Fix NULL pointer dereference in rose_send_frame()
In the Linux kernel, the following vulnerability has been resolved:
rose: Fix NULL pointer dereference in rose_send_frame()
The syzkaller reported an issue:
KASAN: null-ptr-deref in range [0x0000000000000380-0x0000000000000387]
CPU: 0 PID: 4069 Comm: kworker/0:15 Not tainted 6.0.0-syzkaller-02734-g0326074ff465 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Workqueue: rcu_gp srcu_invoke_callbacks
RIP: 0010:rose_send_frame+0x1dd/0x2f0 net/rose/rose_link.c:101
Call Trace:
<IRQ>
rose_transmit_clear_request+0x1d5/0x290 net/rose/rose_link.c:255
rose_rx_call_request+0x4c0/0x1bc0 net/rose/af_rose.c:1009
rose_loopback_timer+0x19e/0x590 net/rose/rose_loopback.c:111
call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474
expire_timers kernel/time/timer.c:1519 [inline]
__run_timers.part.0+0x674/0xa80 kernel/time/timer.c:1790
__run_timers kernel/time/timer.c:1768 [inline]
run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1803
__do_softirq+0x1d0/0x9c8 kernel/softirq.c:571
[...]
</IRQ>
It triggers NULL pointer dereference when 'neigh->dev->dev_addr' is
called in the rose_send_frame(). It's the first occurrence of the
`neigh` is in rose_loopback_timer() as `rose_loopback_neigh', and
the 'dev' in 'rose_loopback_neigh' is initialized sa nullptr.
It had been fixed by commit 3b3fd068c56e3fbea30090859216a368398e39bf
("rose: Fix Null pointer dereference in rose_send_frame()") ever.
But it's introduced by commit 3c53cd65dece47dd1f9d3a809f32e59d1d87b2b8
("rose: check NULL rose_loopback_neigh->loopback") again.
We fix it by add NULL check in rose_transmit_clear_request(). When
the 'dev' in 'neigh' is NULL, we don't reply the request and just
clear it.
syzkaller don't provide repro, and I provide a syz repro like:
r0 = syz_init_net_socket$bt_sco(0x1f, 0x5, 0x2)
ioctl$sock_inet_SIOCSIFFLAGS(r0, 0x8914, &(0x7f0000000180)={'rose0\x00', 0x201})
r1 = syz_init_net_socket$rose(0xb, 0x5, 0x0)
bind$rose(r1, &(0x7f00000000c0)=@full={0xb, @dev, @null, 0x0, [@null, @null, @netrom, @netrom, @default, @null]}, 0x40)
connect$rose(r1, &(0x7f0000000240)=@short={0xb, @dev={0xbb, 0xbb, 0xbb, 0x1, 0x0}, @remote={0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0xcc, 0x1}, 0x1, @netrom={0xbb, 0xbb, 0xbb, 0xbb, 0xbb, 0x0, 0x0}}, 0x1c)
Security readout for executives and security teams
Plain-English summary
This is a Linux kernel availability issue in the ROSE networking code. A local user with some privileges could trigger a NULL pointer dereference and crash the kernel. The impact is denial of service, not data theft or code execution based on the provided sources.
Executive priority
Treat as a normal-priority kernel patching item unless affected systems allow untrusted local users. The business risk is service disruption from local kernel crash, not confirmed compromise. Patch through standard Linux maintenance, with faster handling for shared compute or exposed developer environments.
Technical view
The flaw is CWE-476 in rose_send_frame(), reached through ROSE clear-request handling when neigh->dev is NULL. The listed fix adds a NULL check in rose_transmit_clear_request() and clears the request without replying. CVSS is 5.5, local attack vector, low complexity, low privileges, and high availability impact.
Likely exposure
Exposure is mainly Linux systems running affected kernel versions with ROSE networking support reachable by local users. The source lists multiple affected Linux kernel versions and stable fix commits. Systems without ROSE support, or without local untrusted users, appear less exposed based on the available evidence.
Exploitation context
The source includes syzkaller discovery details and a reproducer, but KEV is false and no cited source states active exploitation. Evidence supports local denial-of-service risk. There is no source-backed evidence here for remote exploitation, privilege escalation, data disclosure, or in-the-wild abuse.
Researcher notes
Do not overstate exploitability. The provided record supports a local, low-privilege availability bug in net/rose and says the earlier fix regressed. The listed remediation is code-level NULL checking in ROSE clear-request handling. The source does not establish active exploitation or broader kernel impact.
Mitigation direction
Update affected Linux kernels to versions containing the referenced stable fixes.
Check distribution vendor advisories for packaged kernel status and backports.
Prioritize shared systems with local shell, container, or multi-user access.
Reduce local access to affected hosts until patched, where operationally feasible.
Validation and detection
Inventory Linux kernel versions against the affected versions in the CVE record.
Confirm whether deployed kernels include one of the referenced stable fix commits.
Check whether ROSE networking support is enabled or available on relevant systems.
Review vendor kernel changelogs for CVE-2022-49916 or the listed commit IDs.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
Conservative CVE-to-ATT&CK context
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cwe · low confidence lookup
CWE-476: Exact CWE lookup
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CWE-476 · source CWE mapping
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.