linux-cve-announce - CVE-2022-49402: ftrace: Clean up hash direct

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Message-ID: <2025022651-CVE-2022-49402-73ee@gregkh>
Date: Wed, 26 Feb 2025 03:11:16 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49402: ftrace: Clean up hash direct_functions on register failures

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2022-49402 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.5 with commit 763e34e74bb7d5c316015e2e39fcc8520bfd071c and fixed in 5.10.121 with commit 82c888e51c2176a06f8b4541cf748ee81aac6e7e
	Issue introduced in 5.5 with commit 763e34e74bb7d5c316015e2e39fcc8520bfd071c and fixed in 5.15.46 with commit cae2978d6907ef2c08b9b15f704e783f7c284713
	Issue introduced in 5.5 with commit 763e34e74bb7d5c316015e2e39fcc8520bfd071c and fixed in 5.17.14 with commit 805e87af946d8d2954171361e64d143ff37a441b
	Issue introduced in 5.5 with commit 763e34e74bb7d5c316015e2e39fcc8520bfd071c and fixed in 5.18.3 with commit a0392833a178cf109a57c2a9d4d531bdfc6cd98f
	Issue introduced in 5.5 with commit 763e34e74bb7d5c316015e2e39fcc8520bfd071c and fixed in 5.19 with commit 7d54c15cb89a29a5f59e5ffc9ee62e6591769ef1

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-49402
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	kernel/trace/ftrace.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/82c888e51c2176a06f8b4541cf748ee81aac6e7e
	https://git.kernel.org/stable/c/cae2978d6907ef2c08b9b15f704e783f7c284713
	https://git.kernel.org/stable/c/805e87af946d8d2954171361e64d143ff37a441b
	https://git.kernel.org/stable/c/a0392833a178cf109a57c2a9d4d531bdfc6cd98f
	https://git.kernel.org/stable/c/7d54c15cb89a29a5f59e5ffc9ee62e6591769ef1