[PATCH net-next] net_sched: netem: do not call qdisc_drop() with a NULL skb

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.com>

If skb_unshare() fails, we call qdisc_drop() with a NULL skb, which
is no longer supported.

Fixes: 520ac30f4551 ("net_sched: drop packets after root qdisc lock is 
released")
Signed-off-by: Eric Dumazet <eduma...@google.com>
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
---
 net/sched/sch_netem.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 
ccca8ca4c722c603e8b8e6052eead51243e590b5..6eac3d8800480a4c463ae8d3b78a4fcfeec8165b
 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -487,10 +487,14 @@ static int netem_enqueue(struct sk_buff *skb, struct 
Qdisc *sch,
                skb = segs;
                segs = segs->next;
 
-               if (!(skb = skb_unshare(skb, GFP_ATOMIC)) ||
-                   (skb->ip_summed == CHECKSUM_PARTIAL &&
-                    skb_checksum_help(skb))) {
-                       rc = qdisc_drop(skb, sch, to_free);
+               skb = skb_unshare(skb, GFP_ATOMIC);
+               if (unlikely(!skb)) {
+                       qdisc_qstats_drop(sch);
+                       goto finish_segs;
+               }
+               if (skb->ip_summed == CHECKSUM_PARTIAL &&
+                   skb_checksum_help(skb)) {
+                       qdisc_drop(skb, sch, to_free);
                        goto finish_segs;
                }