Commit a7fa12d1 authored Oct 18, 2019 by Jakub Kicinski Committed by David S. Miller Oct 19, 2019

net: netem: fix error path for corrupted GSO frames



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 177b8007 ("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: 177b8007 ("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>

parent bd310aca

net/sched/sch_netem.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -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 @@ 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;
		}

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