linux-cve-announce - CVE-2022-49802: ftrace: Fix null pointer dereference in ftrace_add

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Message-ID: <2025050126-CVE-2022-49802-ee41@gregkh>
Date: Thu,  1 May 2025 16:09:52 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-49802: ftrace: Fix null pointer dereference in ftrace_add_mod()

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

In the Linux kernel, the following vulnerability has been resolved:

ftrace: Fix null pointer dereference in ftrace_add_mod()

The @ftrace_mod is allocated by kzalloc(), so both the members {prev,next}
of @ftrace_mode->list are NULL, it's not a valid state to call list_del().
If kstrdup() for @ftrace_mod->{func|module} fails, it goes to @out_free
tag and calls free_ftrace_mod() to destroy @ftrace_mod, then list_del()
will write prev->next and next->prev, where null pointer dereference
happens.

BUG: kernel NULL pointer dereference, address: 0000000000000008
Oops: 0002 [#1] PREEMPT SMP NOPTI
Call Trace:
 <TASK>
 ftrace_mod_callback+0x20d/0x220
 ? do_filp_open+0xd9/0x140
 ftrace_process_regex.isra.51+0xbf/0x130
 ftrace_regex_write.isra.52.part.53+0x6e/0x90
 vfs_write+0xee/0x3a0
 ? __audit_filter_op+0xb1/0x100
 ? auditd_test_task+0x38/0x50
 ksys_write+0xa5/0xe0
 do_syscall_64+0x3a/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Kernel panic - not syncing: Fatal exception

So call INIT_LIST_HEAD() to initialize the list member to fix this issue.

The Linux kernel CVE team has assigned CVE-2022-49802 to this issue.


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

	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 4.14.300 with commit 665b4c6648bf2b91f69b33817f4321cf4c3cafe9
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 4.19.267 with commit b5bfc61f541d3f092b13dedcfe000d86eb8e133c
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 5.4.225 with commit f715f31559b82e3f75ce047fa476de63d8107584
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 5.10.156 with commit 6a14828caddad0d989495a72af678adf60992704
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 5.15.80 with commit 1bea037a1abb23a6729bef36a2265a4565f5ea77
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 6.0.10 with commit 6e50eb4b1807017f6c2d5089064256ce2de8aef1
	Issue introduced in 4.13 with commit 673feb9d76ab3eddde7acfd94b206e321cfc90b9 and fixed in 6.1 with commit 19ba6c8af9382c4c05dc6a0a79af3013b9a35cd0

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-2022-49802
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/665b4c6648bf2b91f69b33817f4321cf4c3cafe9
	https://git.kernel.org/stable/c/b5bfc61f541d3f092b13dedcfe000d86eb8e133c
	https://git.kernel.org/stable/c/f715f31559b82e3f75ce047fa476de63d8107584
	https://git.kernel.org/stable/c/6a14828caddad0d989495a72af678adf60992704
	https://git.kernel.org/stable/c/1bea037a1abb23a6729bef36a2265a4565f5ea77
	https://git.kernel.org/stable/c/6e50eb4b1807017f6c2d5089064256ce2de8aef1
	https://git.kernel.org/stable/c/19ba6c8af9382c4c05dc6a0a79af3013b9a35cd0