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

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

apparmor: fix uninitialised pointer passed to auditloguntrustedstring()

Commit 4a134723f9f1 ("apparmor: move check for aanull file to cover all cases") intrdouced a small bug, where pathname() may pass a potentially uninitialized name to aaauditfile() if the path->dentry had been replaced with aanull.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: errorcode(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]=OOTMODULE [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] auditloguntrustedstring+0x1d/0x40 [51692.242811] [ T24690] commonlsmaudit+0x71/0x1d0 [51692.242816] [ T24690] aaaudit+0x5a/0x170 [51692.242819] [ T24690] aaauditfile+0x18a/0x1b0 [51692.242825] [ T24690] pathname+0xd2/0x100 [51692.242829] [ T24690] profilepathperm.part.0+0x58/0xb0 [51692.242832] [ T24690] aapathperm+0xef/0x150 [51692.242837] [ T24690] apparmorfileopen+0x153/0x2e0 [51692.242840] [ T24690] securityfileopen+0x46/0xd0 [51692.242844] [ T24690] dodentryopen+0xe9/0x4d0 [51692.242848] [ T24690] vfsopen+0x30/0x100

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