From f865c143629d4094866a811dba5f329250bad486 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Sat, 18 Jul 2026 13:09:22 +0800 Subject: [PATCH 1/2] audit: fix potential integer overflow in audit_log_n_string() audit_log_n_string() computes new_len as "slen + 3" (enclosing quotes plus the NUL terminator) and stores it into an int, while slen is a size_t. For a sufficiently large slen the addition can overflow and/or the result be truncated when assigned to the int new_len, so the "new_len > avail" check can be bypassed and the subsequent memcpy(ptr, string, slen) can write past the skb tail. This is the same class of bug that was fixed for the hex sibling in commit 65dfde57d1e2 ("audit: fix potential integer overflow in audit_log_n_hex()"); both helpers are reached through audit_log_n_untrustedstring() with the same length source. Make new_len a size_t and use check_add_overflow() to catch the overflow, mirroring the audit_log_n_hex() fix. No functional change for the in-tree callers, which all pass bounded lengths. Cc: stable@vger.kernel.org Fixes: 168b7173959f ("AUDIT: Clean up logging of untrusted strings") Signed-off-by: Zhan Xusheng Signed-off-by: Paul Moore --- kernel/audit.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/audit.c b/kernel/audit.c index 562476937fa7..9412af9144bc 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -2120,7 +2120,8 @@ void audit_log_n_hex(struct audit_buffer *ab, const unsigned char *buf, void audit_log_n_string(struct audit_buffer *ab, const char *string, size_t slen) { - int avail, new_len; + int avail; + size_t new_len; unsigned char *ptr; struct sk_buff *skb; @@ -2130,7 +2131,13 @@ void audit_log_n_string(struct audit_buffer *ab, const char *string, BUG_ON(!ab->skb); skb = ab->skb; avail = skb_tailroom(skb); - new_len = slen + 3; /* enclosing quotes + null terminator */ + + /* enclosing quotes + null terminator */ + if (check_add_overflow(slen, 3, &new_len)) { + audit_log_format(ab, "?"); + return; + } + if (new_len > avail) { avail = audit_expand(ab, new_len); if (!avail) From 246df90b5f1a8a6e6abbd2f058b029558720adec Mon Sep 17 00:00:00 2001 From: Luxiao Xu Date: Tue, 21 Jul 2026 23:37:41 +0800 Subject: [PATCH 2/2] audit: fix potential use-after-free in audit_del_rule() `audit_del_rule()` destroys `e->rule.exe` via `audit_remove_mark_rule()` before unlinking the rule from RCU-visible filter lists and waiting for a grace period. Concurrent readers in `audit_filter()` and `audit_filter_rules()` still dereference `e->rule.exe`, while the fsnotify mark can be freed on an independent lifetime path. This creates a use-after-free window during rule deletion. Fix this by unlinking the rule from the RCU-visible lists and invoking `synchronize_rcu()` before calling `audit_remove_mark_rule()` (and other rule removal helpers). This ensures that all existing RCU readers have exited the critical section before any underlying resources are destroyed. Cc: stable@vger.kernel.org Fixes: 34d99af52ad4 ("audit: implement audit by executable") Reported-by: Vega Assisted-by: Codex:gpt-5.4 Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Signed-off-by: Paul Moore --- kernel/auditfilter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index 4401119b5275..7f791afe5791 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -1045,6 +1045,10 @@ int audit_del_rule(struct audit_entry *entry) goto out; } + list_del_rcu(&e->list); + list_del(&e->rule.list); + synchronize_rcu(); + if (e->rule.watch) audit_remove_watch_rule(&e->rule); @@ -1062,8 +1066,6 @@ int audit_del_rule(struct audit_entry *entry) audit_signals--; #endif - list_del_rcu(&e->list); - list_del(&e->rule.list); call_rcu(&e->rcu, audit_free_rule_rcu); out: