Mon, Jul 29, 2019 at 04:21:57AM CEST, [email protected] wrote:
>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.
>
>Signed-off-by: Jia-Ju Bai <[email protected]>
Fixes tag, please?
>---
> net/sched/sch_codel.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
>diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
>index 25ef172c23df..30169b3adbbb 100644
>--- a/net/sched/sch_codel.c
>+++ b/net/sched/sch_codel.c
>@@ -71,10 +71,10 @@ static struct sk_buff *dequeue_func(struct codel_vars
>*vars, void *ctx)
> 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;
> }
>
>--
>2.17.0
>
