diff mbox series

[net,v2,1/2] net: netem: fix error path for corrupted GSO frames

Message ID 20191018161658.26481-2-jakub.kicinski@netronome.com
State Accepted
Delegated to: David Miller
Headers show
Series net: netem: fix further issues with packet corruption | expand

Commit Message

Jakub Kicinski Oct. 18, 2019, 4:16 p.m. UTC 
To corrupt a GSO frame we first perform segmentation.  We then
proceed using the first segment instead of the full GSO skb and
requeue the rest of the segments as separate packets.

If there are any issues with processing the first segment we
still want to process the rest, therefore we jump to the
finish_segs label.

Commit 177b8007463c ("net: netem: fix backlog accounting for
corrupted GSO frames") started using the pointer to the first
segment in the "rest of segments processing", but as mentioned
above the first segment may had already been freed at this point.

Backlog corrections for parent qdiscs have to be adjusted.

Fixes: 177b8007463c ("net: netem: fix backlog accounting for corrupted GSO frames")
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
---
 net/sched/sch_netem.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0e44039e729c..942eb17f413c 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -509,6 +509,7 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 		if (skb->ip_summed == CHECKSUM_PARTIAL &&
 		    skb_checksum_help(skb)) {
 			qdisc_drop(skb, sch, to_free);
+			skb = NULL;
 			goto finish_segs;
 		}
 
@@ -593,9 +594,10 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 finish_segs:
 	if (segs) {
 		unsigned int len, last_len;
-		int nb = 0;
+		int nb;
 
-		len = skb->len;
+		len = skb ? skb->len : 0;
+		nb = skb ? 1 : 0;
 
 		while (segs) {
 			skb2 = segs->next;
@@ -612,7 +614,8 @@  static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
 			}
 			segs = skb2;
 		}
-		qdisc_tree_reduce_backlog(sch, -nb, prev_len - len);
+		/* Parent qdiscs accounted for 1 skb of size @prev_len */
+		qdisc_tree_reduce_backlog(sch, -(nb - 1), -(len - prev_len));
 	}
 	return NET_XMIT_SUCCESS;
 }