Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix use-after-free in rawdata dedup loop aa_replace_profiles() walks ns->rawdata_list to dedup the incoming policy blob against entries already attached to existing profiles. Per the kernel-doc on struct aa_loaddata, list membership does not hold a reference: profiles hold pcount, and when the last pcount drops, do_ploaddata_rmfs() is queued on a workqueue that takes ns->lock and removes the entry. Between dropping the last pcount and the workqueue running, an entry remains on the list with pcount == 0. aa_get_profile_loaddata() is an unconditional kref_get() on pcount, so when the dedup loop hits such an entry, refcount hardening reports refcount_t: addition on 0; use-after-free. inside aa_replace_profiles(), and the poisoned counter then trips "saturated" and "underflow" warnings on the subsequent uses of the same loaddata. Before commit a0b7091c4de4 ("apparmor: fix race on rawdata dereference") the dedup path used a get_unless_zero-style helper on a single counter, so the existing "if (tmp)" guard was meaningful. The split-refcount refactor introduced aa_get_profile_loaddata(), which has plain kref_get() semantics, and the guard quietly became a no-op. Introduce aa_get_profile_loaddata_not0(), matching the existing _not0 convention used by aa_get_profile_not0(), and use it for the rawdata_list dedup lookup so dying entries are skipped. Reproduced on x86_64 with v7.1-rc5 in QEMU+KVM running Ubuntu 24.04 + stress-ng 0.17.06: stress-ng --apparmor 1 --klog-check --timeout 60s Without this patch the three refcount_t warnings fire within a few seconds. With it the same 60 s run is clean. Coverage is a smoke-test only; a longer soak with CONFIG_KASAN, CONFIG_KCSAN and CONFIG_PROVE_LOCKING would be welcome from anyone with the cycles.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 3b8e77c7abab40e6de9ad9de730d77984a498840 before 643221da57dbb1a8fd800610331cf1ec27969f71; affected d9d8560b9b7932f8cffc4c068c14289220900f79 before b17f0c59cc1525765625cf07d0391b7f9c1ed7e5; affected 6b6ba87579c7e7c669e0bec91823e7fb693bc5df before a7a2890028f16e5b0af0bb005d80fcb32559cca3; affected 6ef1f2926c41ab96952d9696d55a052f1b3a9418 before 15fd83a1e42ede15070968806bb6c8b1a5170688; affected f9761add6d100962a23996cb68f3d6abdd4d1815 before ce261a20b41db522e320a41bbf1292bf85af66df; affected af782cc8871e3683ddd5a3cd2f7df526599863a9 before c3ca2631073b2cef06824fd2bfc452ff7a1023de; affected a0b7091c4de45a7325c8780e6934a894f92ac86b before 5e34fa9f6f7cd688ae153fff13139a5cf2d42339; affected a0b7091c4de45a7325c8780e6934a894f92ac86b before 6f060496d03e4dc560a40f73770bd08335cb7a27; affected 763e838adc3c7ec5a7df2990ce84cad951e42721; affected 5.10.253 before 5.10.261; affected 5.15.203 before 5.15.212; affected 6.1.169 before 6.1.177; affected 6.6.130 before 6.6.144; affected 6.12.77 before 6.12.95; affected 6.18.18 before 6.18.38; affected 6.19.8 before 6.20 |
| Linux / Linux | affected 7.0; unaffected 0 before 7.0; unaffected 5.10.261 through 5.10.*; unaffected 5.15.212 through 5.15.*; unaffected 6.1.177 through 6.1.*; unaffected 6.6.144 through 6.6.*; unaffected 6.12.95 through 6.12.*; unaffected 6.18.38 through 6.18.*; unaffected 7.1.3 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/643221da57dbb1a8fd800610331cf1ec27969f71
- https://git.kernel.org/stable/c/b17f0c59cc1525765625cf07d0391b7f9c1ed7e5
- https://git.kernel.org/stable/c/a7a2890028f16e5b0af0bb005d80fcb32559cca3
- https://git.kernel.org/stable/c/15fd83a1e42ede15070968806bb6c8b1a5170688
- https://git.kernel.org/stable/c/ce261a20b41db522e320a41bbf1292bf85af66df
- https://git.kernel.org/stable/c/c3ca2631073b2cef06824fd2bfc452ff7a1023de
- https://git.kernel.org/stable/c/5e34fa9f6f7cd688ae153fff13139a5cf2d42339
- https://git.kernel.org/stable/c/6f060496d03e4dc560a40f73770bd08335cb7a27