[PATCH] audit: don't create audit log when audit_backlog_limit is zero

[Gao feng <gaofeng@cn.fujitsu.com>]

As the man page of auditctl said:
"
-b backlog
              Set max number of outstanding audit buffers allowed (Kernel Default=64)
	      If all buffers are full, the failure flag is consulted by the kernel
              for action.
"

So if audit_backlog_limit is zero, it means no audit buffer
should be allocated.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
---
 kernel/audit.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/audit.c b/kernel/audit.c
index 7b0e23a..bbb4000 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -1104,14 +1104,16 @@ struct audit_buffer *audit_log_start(struct audit_context *ctx, gfp_t gfp_mask,
 	if (unlikely(audit_filter_type(type)))
 		return NULL;
 
+	if (!audit_backlog_limit)
+		return NULL;
+
 	if (gfp_mask & __GFP_WAIT)
 		reserve = 0;
 	else
 		reserve = 5; /* Allow atomic callers to go up to five
 				entries over the normal backlog limit */
 
-	while (audit_backlog_limit
-	       && skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
+	while (skb_queue_len(&audit_skb_queue) > audit_backlog_limit + reserve) {
 		if (gfp_mask & __GFP_WAIT && audit_backlog_wait_time) {
 			unsigned long sleep_time;
 
-- 
1.8.3.1