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CVE Record

CVE-2022-49892: ftrace: Fix use-after-free for dynamic ftrace_ops

In the Linux kernel, the following vulnerability has been resolved: ftrace: Fix use-after-free for dynamic ftrace_ops KASAN reported a use-after-free with ftrace ops [1]. It was found from vmcore that perf had registered two ops with the same content successively, both dynamic. After unregistering the second ops, a use-after-free occurred. In ftrace_shutdown(), when the second ops is unregistered, the FTRACE_UPDATE_CALLS command is not set because there is another enabled ops with the same content. Also, both ops are dynamic and the ftrace callback function is ftrace_ops_list_func, so the FTRACE_UPDATE_TRACE_FUNC command will not be set. Eventually the value of 'command' will be 0 and ftrace_shutdown() will skip the rcu synchronization. However, ftrace may be activated. When the ops is released, another CPU may be accessing the ops. Add the missing synchronization to fix this problem. [1] BUG: KASAN: use-after-free in __ftrace_ops_list_func kernel/trace/ftrace.c:7020 [inline] BUG: KASAN: use-after-free in ftrace_ops_list_func+0x2b0/0x31c kernel/trace/ftrace.c:7049 Read of size 8 at addr ffff56551965bbc8 by task syz-executor.2/14468 CPU: 1 PID: 14468 Comm: syz-executor.2 Not tainted 5.10.0 #7 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x40c arch/arm64/kernel/stacktrace.c:132 show_stack+0x30/0x40 arch/arm64/kernel/stacktrace.c:196 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b4/0x248 lib/dump_stack.c:118 print_address_description.constprop.0+0x28/0x48c mm/kasan/report.c:387 __kasan_report mm/kasan/report.c:547 [inline] kasan_report+0x118/0x210 mm/kasan/report.c:564 check_memory_region_inline mm/kasan/generic.c:187 [inline] __asan_load8+0x98/0xc0 mm/kasan/generic.c:253 __ftrace_ops_list_func kernel/trace/ftrace.c:7020 [inline] ftrace_ops_list_func+0x2b0/0x31c kernel/trace/ftrace.c:7049 ftrace_graph_call+0x0/0x4 __might_sleep+0x8/0x100 include/linux/perf_event.h:1170 __might_fault mm/memory.c:5183 [inline] __might_fault+0x58/0x70 mm/memory.c:5171 do_strncpy_from_user lib/strncpy_from_user.c:41 [inline] strncpy_from_user+0x1f4/0x4b0 lib/strncpy_from_user.c:139 getname_flags+0xb0/0x31c fs/namei.c:149 getname+0x2c/0x40 fs/namei.c:209 [...] Allocated by task 14445: kasan_save_stack+0x24/0x50 mm/kasan/common.c:48 kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc mm/kasan/common.c:479 [inline] __kasan_kmalloc.constprop.0+0x110/0x13c mm/kasan/common.c:449 kasan_kmalloc+0xc/0x14 mm/kasan/common.c:493 kmem_cache_alloc_trace+0x440/0x924 mm/slub.c:2950 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:675 [inline] perf_event_alloc.part.0+0xb4/0x1350 kernel/events/core.c:11230 perf_event_alloc kernel/events/core.c:11733 [inline] __do_sys_perf_event_open kernel/events/core.c:11831 [inline] __se_sys_perf_event_open+0x550/0x15f4 kernel/events/core.c:11723 __arm64_sys_perf_event_open+0x6c/0x80 kernel/events/core.c:11723 [...] Freed by task 14445: kasan_save_stack+0x24/0x50 mm/kasan/common.c:48 kasan_set_track+0x24/0x34 mm/kasan/common.c:56 kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:358 __kasan_slab_free.part.0+0x11c/0x1b0 mm/kasan/common.c:437 __kasan_slab_free mm/kasan/common.c:445 [inline] kasan_slab_free+0x2c/0x40 mm/kasan/common.c:446 slab_free_hook mm/slub.c:1569 [inline] slab_free_freelist_hook mm/slub.c:1608 [inline] slab_free mm/slub.c:3179 [inline] kfree+0x12c/0xc10 mm/slub.c:4176 perf_event_alloc.part.0+0xa0c/0x1350 kernel/events/core.c:11434 perf_event_alloc kernel/events/core.c:11733 [inline] __do_sys_perf_event_open kernel/events/core.c:11831 [inline] __se_sys_perf_event_open+0x550/0x15f4 kernel/events/core.c:11723 [...]

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory safety bug in ftrace, the function tracing subsystem. Under a specific perf/ftrace registration sequence, the kernel can keep using a tracing operation after it has been freed. The public record does not provide CVSS, active exploitation evidence, or a complete distro impact map.

Executive priority

Treat this as a kernel maintenance item with moderate urgency. It is not listed as exploited, but kernel use-after-free issues can affect system stability and may become more serious depending on local access and distro configuration.

Technical view

The flaw is a use-after-free in dynamic ftrace_ops handling. When duplicate dynamic ops are unregistered, ftrace_shutdown() could skip RCU synchronization because no update command was set, while another CPU could still access the released ops through ftrace_ops_list_func.

Likely exposure

Exposure is limited to Linux systems running affected kernel builds, especially where perf and ftrace functionality are available. The bundle lists Linux kernel affected version markers including 4.14, 5.10.154, 5.15.78, 6.0.8, and 6.1, but distro backports require vendor confirmation.

Exploitation context

The source describes KASAN detection and syz-executor activity, not confirmed real-world exploitation. KEV is false. The evidence supports a local kernel memory safety issue involving perf_event_open and ftrace, but does not prove practical privilege escalation or remote exploitability.

Researcher notes

Key uncertainty is exploitability beyond the KASAN/syzkaller-style report. The record identifies the missing RCU synchronization path, but lacks CVSS, CWE, exploit status, and distro-specific fixed package versions. Validate by commit presence, not upstream version alone.

Mitigation direction

  • Update to a vendor kernel containing the referenced stable ftrace synchronization fix.
  • Check distro advisories because kernel fixes are often backported without changing upstream version numbers.
  • Review whether untrusted users can access perf or tracing interfaces under vendor-supported policy.
  • Prioritize systems that allow local shell access, containers with broad kernel interfaces, or developer workloads.

Validation and detection

  • Inventory Linux kernel versions and map them to vendor security advisories for CVE-2022-49892.
  • Confirm whether the referenced stable commits are present in deployed kernel source or package changelogs.
  • Check host policy for unprivileged perf and tracing access where vendor guidance supports doing so.
  • Monitor kernel logs for KASAN, tracing, or ftrace-related instability on test systems.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxedb096e00724f02db5f6ec7900f3bbd465c6c76f, edb096e00724f02db5f6ec7900f3bbd465c6c76f, edb096e00724f02db5f6ec7900f3bbd465c6c76f, edb096e00724f02db5f6ec7900f3bbd465c6c76f, a60e407b961e818541ff7924afa8e51fbdb21a61, ed1bf4397d2219d4b9ec2d5517416ba102186650, 100553e197e2c41eccf9fa04b2be9cd11ae21215, 30d3c1c9c9dd31b3c3a5aa0f4f40f1e321c6c791, 4.1.45, 4.4.89, 4.9.52, 4.13.4unaffected
LinuxLinux4.14, 0, 5.10.154, 5.15.78, 6.0.8, 6.1affected
Weakness

CWE details

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