CVE-2026-72455: apparmor: fix uninitialised pointer passed to audit_log_untrustedstring()

CVE-2026-72455: apparmor: fix uninitialised pointer passed to audit_log_untrustedstring()

[Greg Kroah-Hartman]

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

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

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

apparmor: fix uninitialised pointer passed to audit_log_untrustedstring()

Commit 4a134723f9f1 ("apparmor: move check for aa_null file to cover all cases")
intrdouced a small bug, where path_name() may pass a potentially uninitialized
*name to aa_audit_file() if the path->dentry had been replaced with
aa_null.dentry earlier on. This can lead to page fault like one observed on
7.0.2 openSUSE Tumbleweed kernel:

[51692.242756] [  T24690] BUG: unable to handle page fault for address: 0000000f00000003
[51692.242762] [  T24690] #PF: supervisor read access in kernel mode
[51692.242763] [  T24690] #PF: error_code(0x0000) - not-present page
[51692.242765] [  T24690] PGD 0 P4D 0
[51692.242768] [  T24690] Oops: Oops: 0000 [#1] SMP NOPTI
[51692.242772] [  T24690] CPU: 3 UID: 1020 PID: 24690 Comm: snap-confine Tainted: G           O        7.0.2-1-default #1 PREEMPT(full) openSUSE Tumbleweed  ab90b4c9940707f9cafa19bdad80b2cec52dbe51
[51692.242775] [  T24690] Tainted: [O]=OOT_MODULE
[51692.242777] [  T24690] Hardware name: Framework Laptop 13 (AMD Ryzen 7040Series)/FRANMDCP05, BIOS 03.18 01/08/2026
[51692.242778] [  T24690] RIP: 0010:strlen+0x4/0x30
[51692.242783] [  T24690] Code: f7 75 ec 31 c0 e9 17 9f 00 ff 48 89 f8 e9 0f 9f 00 ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <80> 3f 00 74 18 48 89 f8 0f 1f 40 00 48 83 c0 01 80 38 00 75 f7 48
[51692.242785] [  T24690] RSP: 0018:ffffd015eb1e3608 EFLAGS: 00010282
[51692.242787] [  T24690] RAX: 0000000000000000 RBX: ffff89796198a360 RCX: 0000000000000000
[51692.242788] [  T24690] RDX: 00000000000000d1 RSI: 0000000f00000003 RDI: 0000000f00000003
[51692.242790] [  T24690] RBP: ffffffffb7ede090 R08: 00000000000005f5 R09: 0000000000000000
[51692.242791] [  T24690] R10: 0000000000000000 R11: 0000000000000000 R12: ffffd015eb1e3700
[51692.242792] [  T24690] R13: ffff8977a22bc380 R14: ffffffffb7ec5190 R15: ffff8977a0c8aa80
[51692.242794] [  T24690] FS:  0000000000000000(0000) GS:ffff897f640d8000(0000) knlGS:0000000000000000
[51692.242796] [  T24690] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[51692.242797] [  T24690] CR2: 0000000f00000003 CR3: 00000006ad15f000 CR4: 0000000000f50ef0
[51692.242799] [  T24690] PKRU: 55555554
[51692.242800] [  T24690] Call Trace:
[51692.242802] [  T24690]  <TASK>
[51692.242804] [  T24690]  audit_log_untrustedstring+0x1d/0x40
[51692.242811] [  T24690]  common_lsm_audit+0x71/0x1d0
[51692.242816] [  T24690]  aa_audit+0x5a/0x170
[51692.242819] [  T24690]  aa_audit_file+0x18a/0x1b0
[51692.242825] [  T24690]  path_name+0xd2/0x100
[51692.242829] [  T24690]  profile_path_perm.part.0+0x58/0xb0
[51692.242832] [  T24690]  aa_path_perm+0xef/0x150
[51692.242837] [  T24690]  apparmor_file_open+0x153/0x2e0
[51692.242840] [  T24690]  security_file_open+0x46/0xd0
[51692.242844] [  T24690]  do_dentry_open+0xe9/0x4d0
[51692.242848] [  T24690]  vfs_open+0x30/0x100

While here, initialise variables which are passed down to path_name().

The Linux kernel CVE team has assigned CVE-2026-72455 to this issue.


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

	Issue introduced in 6.18.14 with commit b2a8011ae8749215f3939881239b454728a2d88b and fixed in 6.18.40 with commit 2791dd42d41e38805572b12116f721c97c4fcc0c
	Issue introduced in 7.0 with commit 4a134723f9f1ad2f3621566259db673350d19cb1 and fixed in 7.1.5 with commit a5c79d44ef19203bd7cf6f3de8ff088112ebff95
	Issue introduced in 7.0 with commit 4a134723f9f1ad2f3621566259db673350d19cb1 and fixed in 7.2-rc1 with commit bcd1b34c21748531a3febaf7440632b89d8deab7
	Issue introduced in 6.19.4 with commit d276f52ecaf854e41549311e93802afea0abab5b

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-2026-72455
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:
	security/apparmor/file.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/2791dd42d41e38805572b12116f721c97c4fcc0c
	https://git.kernel.org/stable/c/a5c79d44ef19203bd7cf6f3de8ff088112ebff95
	https://git.kernel.org/stable/c/bcd1b34c21748531a3febaf7440632b89d8deab7