Re: [PATCH v2] audit: fix exe mark UAF in kill_rules()

[sashiko-bot@kernel.org]

> kill_rules() removes mixed AUDIT_DIR and AUDIT_EXE rules when an audit
> tree is pruned. It drops entry->rule.exe before removing the rule from
> the RCU-visible filter lists.
> 
> After a rule has been installed with AUDIT_ADD_RULE, which requires
> CAP_AUDIT_CONTROL, removing the watched directory can race with another
> task that is still evaluating the rule. In that case, fsnotify can free
> the executable mark before the reader reaches audit_mark_compare(),
> causing a use-after-free.
> 
> KASAN reports:
> 
>     BUG: KASAN: slab-use-after-free in audit_mark_compare+0x8d/0xa0
> 
> Unlink the published rules from the RCU-visible lists and retain them
> on tree->rules for cleanup. If any rule has an executable mark, wait for
> a single RCU grace period before removing the marks and scheduling the
> entries for freeing. Otherwise, call_rcu() already provides the required
> deferred freeing without a synchronous wait.
> 
> Fixes: 34d99af52ad4 ("audit: implement audit by executable")
> Assisted-by: Codex:gpt-5
> Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260922202734.1344770-2-Jeremy.Jean@oss.cyber.gouv.fr?part=1