[PATCH 1/2] fix audit skb leak on congested netlink socket
When auditd is congested the kernel's audit system leaks skb's. First,
it takes them off the audit_buffer sklist at which point they are lost,
second, it allocates a new skb with 0 length payload. Then (likely still
congested), it repeats this losing the new skb. Plug the leak by making
sure to requeue the skb, and avoid audit_log_move() on 0 len audit_buffer.
Signed-off-by: Chris Wright <chrisw(a)osdl.org>
===== kernel/audit.c 1.6 vs edited =====
--- 1.6/kernel/audit.c 2005-01-20 20:56:04 -08:00
+++ edited/kernel/audit.c 2005-01-25 14:34:32 -08:00
@@ -494,6 +494,10 @@ static void audit_log_move(struct audit_
char *start;
int extra = ab->nlh ? 0 : NLMSG_SPACE(0);
+ /* possible resubmission */
+ if (ab->len == 0)
+ return;
+
skb = skb_peek(&ab->sklist);
if (!skb || skb_tailroom(skb) <= ab->len + extra) {
skb = alloc_skb(2 * ab->len + extra, GFP_ATOMIC);
@@ -535,6 +539,7 @@ static inline int audit_log_drain(struct
}
if (retval == -EAGAIN && ab->count < 5) {
++ab->count;
+ skb_queue_tail(&ab->sklist, skb);
audit_log_end_irq(ab);
return 1;
}