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CVE Record

CVE-2022-49402: ftrace: Clean up hash direct_functions on register failures

In the Linux kernel, the following vulnerability has been resolved: ftrace: Clean up hash direct_functions on register failures We see the following GPF when register_ftrace_direct fails: [ ] general protection fault, probably for non-canonical address \ 0x200000000000010: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI [...] [ ] RIP: 0010:ftrace_find_rec_direct+0x53/0x70 [ ] Code: 48 c1 e0 03 48 03 42 08 48 8b 10 31 c0 48 85 d2 74 [...] [ ] RSP: 0018:ffffc9000138bc10 EFLAGS: 00010206 [ ] RAX: 0000000000000000 RBX: ffffffff813e0df0 RCX: 000000000000003b [ ] RDX: 0200000000000000 RSI: 000000000000000c RDI: ffffffff813e0df0 [ ] RBP: ffffffffa00a3000 R08: ffffffff81180ce0 R09: 0000000000000001 [ ] R10: ffffc9000138bc18 R11: 0000000000000001 R12: ffffffff813e0df0 [ ] R13: ffffffff813e0df0 R14: ffff888171b56400 R15: 0000000000000000 [ ] FS: 00007fa9420c7780(0000) GS:ffff888ff6a00000(0000) knlGS:000000000 [ ] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ ] CR2: 000000000770d000 CR3: 0000000107d50003 CR4: 0000000000370ee0 [ ] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ ] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ ] Call Trace: [ ] <TASK> [ ] register_ftrace_direct+0x54/0x290 [ ] ? render_sigset_t+0xa0/0xa0 [ ] bpf_trampoline_update+0x3f5/0x4a0 [ ] ? 0xffffffffa00a3000 [ ] bpf_trampoline_link_prog+0xa9/0x140 [ ] bpf_tracing_prog_attach+0x1dc/0x450 [ ] bpf_raw_tracepoint_open+0x9a/0x1e0 [ ] ? find_held_lock+0x2d/0x90 [ ] ? lock_release+0x150/0x430 [ ] __sys_bpf+0xbd6/0x2700 [ ] ? lock_is_held_type+0xd8/0x130 [ ] __x64_sys_bpf+0x1c/0x20 [ ] do_syscall_64+0x3a/0x80 [ ] entry_SYSCALL_64_after_hwframe+0x44/0xae [ ] RIP: 0033:0x7fa9421defa9 [ ] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 9 f8 [...] [ ] RSP: 002b:00007ffed743bd78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 [ ] RAX: ffffffffffffffda RBX: 00000000069d2480 RCX: 00007fa9421defa9 [ ] RDX: 0000000000000078 RSI: 00007ffed743bd80 RDI: 0000000000000011 [ ] RBP: 00007ffed743be00 R08: 0000000000bb7270 R09: 0000000000000000 [ ] R10: 00000000069da210 R11: 0000000000000246 R12: 0000000000000001 [ ] R13: 00007ffed743c4b0 R14: 00000000069d2480 R15: 0000000000000001 [ ] </TASK> [ ] Modules linked in: klp_vm(OK) [ ] ---[ end trace 0000000000000000 ]--- One way to trigger this is: 1. load a livepatch that patches kernel function xxx; 2. run bpftrace -e 'kfunc:xxx {}', this will fail (expected for now); 3. repeat #2 => gpf. This is because the entry is added to direct_functions, but not removed. Fix this by remove the entry from direct_functions when register_ftrace_direct fails. Also remove the last trailing space from ftrace.c, so we don't have to worry about it anymore.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2022-49402 is a Linux kernel reliability flaw in ftrace cleanup. When a direct ftrace registration fails, stale state can remain and a later tracing operation can crash the kernel. Business impact is mainly potential host instability or denial of service where affected kernel tracing, livepatch, and BPF functionality are available.

Executive priority

Prioritize routine kernel patching, with faster handling for production hosts that use livepatching, observability tooling, or BPF tracing. The evidence supports crash risk, not confirmed data theft or remote compromise.

Technical view

The bug leaves an entry in ftrace direct_functions when register_ftrace_direct fails. A later ftrace_find_rec_direct lookup can hit corrupted stale state and trigger a general protection fault. The provided trace reaches this path through BPF trampoline attachment. Kernel stable commits fix the failure path by removing the direct_functions entry on registration failure.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions with relevant ftrace, livepatch, and BPF tracing paths enabled or usable. The bundle does not identify remote exposure, affected distributions, container escape conditions, or required privileges.

Exploitation context

The source describes a reproducible crash scenario involving livepatch and BPF tracing, but provides no KEV listing and no cited evidence of active exploitation. Treat this as a stability and local denial-of-service risk unless vendor guidance says otherwise.

Researcher notes

The core issue is incomplete cleanup on register_ftrace_direct failure. The public description includes a kernel GPF and a specific BPF trampoline call path. Severity, CVSS, CWE, distribution impact, and exploit-in-the-wild evidence are not present in the supplied bundle.

Mitigation direction

  • Update affected Linux kernels to vendor builds containing the referenced stable fixes.
  • Check distribution advisories for exact fixed package versions and reboot requirements.
  • Restrict access to BPF tracing and livepatch capabilities to trusted administrators.
  • Monitor kernel logs for ftrace, BPF trampoline, or general protection fault messages.

Validation and detection

  • Inventory Linux kernel versions across servers, containers hosts, and appliances.
  • Map installed kernels against vendor advisories referencing CVE-2022-49402.
  • Confirm whether ftrace, BPF tracing, and livepatch are enabled or operationally used.
  • Verify the fixed kernel is running after update, not only installed.
  • Review crash logs for matching ftrace_find_rec_direct or register_ftrace_direct traces.
Prepared
Confidence
medium
Sources
7

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

Conservative CVE-to-ATT&CK context

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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
6Source 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
LinuxLinux763e34e74bb7d5c316015e2e39fcc8520bfd071c, 763e34e74bb7d5c316015e2e39fcc8520bfd071c, 763e34e74bb7d5c316015e2e39fcc8520bfd071c, 763e34e74bb7d5c316015e2e39fcc8520bfd071c, 763e34e74bb7d5c316015e2e39fcc8520bfd071cunaffected
LinuxLinux5.5, 0, 5.10.121, 5.15.46, 5.17.14, 5.18.3, 5.19affected
Weakness

CWE details

No CWE listed

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