3.16.77-rc1 review patch. If anyone has any objections, please let me know.
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From: Jakub Kicinski jakub.kicinski@netronome.com
commit a7fa12d15855904aff1716e1fc723c03ba38c5cc upstream.
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 Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/sched/sch_netem.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -506,6 +506,7 @@ static int netem_enqueue(struct sk_buff (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))) { rc = qdisc_drop(skb, sch); + skb = NULL; goto finish_segs; }
@@ -576,9 +577,10 @@ static int netem_enqueue(struct sk_buff 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; @@ -595,7 +597,8 @@ finish_segs: } 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; }