---
id: CVE-2022-49402
title: 'ftrace: Clean up hash direct_functions on register failures'
summary: |-
  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…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c <
    82c888e51c2176a06f8b4541cf748ee81aac6e7e
  - >-
    Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c <
    cae2978d6907ef2c08b9b15f704e783f7c284713
  - >-
    Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c <
    805e87af946d8d2954171361e64d143ff37a441b
  - >-
    Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c <
    a0392833a178cf109a57c2a9d4d531bdfc6cd98f
  - >-
    Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c <
    7d54c15cb89a29a5f59e5ffc9ee62e6591769ef1
  - Linux 5.5
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T19:45:23.106164Z'
published: '2025-02-26'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T19:49:39.212Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2022-49402'
references:
  - url: 'https://git.kernel.org/stable/c/82c888e51c2176a06f8b4541cf748ee81aac6e7e'
  - url: 'https://git.kernel.org/stable/c/cae2978d6907ef2c08b9b15f704e783f7c284713'
  - url: 'https://git.kernel.org/stable/c/805e87af946d8d2954171361e64d143ff37a441b'
  - url: 'https://git.kernel.org/stable/c/a0392833a178cf109a57c2a9d4d531bdfc6cd98f'
  - url: 'https://git.kernel.org/stable/c/7d54c15cb89a29a5f59e5ffc9ee62e6591769ef1'
tags:
  - cve.org
epss: 0.00281
epssPercentile: 0.20699
ingestedAt: '2026-11-05T22:38:31.575Z'
---

## Overview

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.

## Affected

- `Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c < 82c888e51c2176a06f8b4541cf748ee81aac6e7e`
- `Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c < cae2978d6907ef2c08b9b15f704e783f7c284713`
- `Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c < 805e87af946d8d2954171361e64d143ff37a441b`
- `Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c < a0392833a178cf109a57c2a9d4d531bdfc6cd98f`
- `Linux >= 763e34e74bb7d5c316015e2e39fcc8520bfd071c < 7d54c15cb89a29a5f59e5ffc9ee62e6591769ef1`
- `Linux 5.5`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.