From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
[ Upstream commit 051c7b39be4a91f6b7d8c4548444e4b850f1f56c ]
In dequeue_func(), there is an if statement on line 74 to check whether
skb is NULL:
if (skb)
When skb is NULL, it is used on line 77:
prefetch(&skb->end);
Thus, a possible null-pointer dereference may occur.
To fix this bug, skb->end is used when skb is not NULL.
This bug is found by a static analysis tool STCheck written by us.
Fixes: 76e3cc126bb2 ("codel: Controlled Delay AQM")
Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sched/sch_codel.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -71,10 +71,10 @@ static struct sk_buff *dequeue_func(stru
struct Qdisc *sch = ctx;
struct sk_buff *skb = __qdisc_dequeue_head(&sch->q);
- if (skb)
+ if (skb) {
sch->qstats.backlog -= qdisc_pkt_len(skb);
-
- prefetch(&skb->end); /* we'll need skb_shinfo() */
+ prefetch(&skb->end); /* we'll need skb_shinfo() */
+ }
return skb;
}
