[PATCH net-next] sctp: Fix SKB list traversal in sctp_intl_store_ordered().

[David Miller]

Same change as made to sctp_intl_store_reasm().

To be fully correct, an iterator has an undefined value when something
like skb_queue_walk() naturally terminates.

This will actually matter when SKB queues are converted over to
list_head.

Formalize what this code ends up doing with the current
implementation.

Signed-off-by: David S. Miller <da...@davemloft.net>
---
 net/sctp/stream_interleave.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/net/sctp/stream_interleave.c b/net/sctp/stream_interleave.c
index 368d9c33fde1..2b499a85db0e 100644
--- a/net/sctp/stream_interleave.c
+++ b/net/sctp/stream_interleave.c
@@ -390,7 +390,7 @@ static void sctp_intl_store_ordered(struct sctp_ulpq *ulpq,
                                    struct sctp_ulpevent *event)
 {
        struct sctp_ulpevent *cevent;
-       struct sk_buff *pos;
+       struct sk_buff *pos, *loc;
 
        pos = skb_peek_tail(&ulpq->lobby);
        if (!pos) {
@@ -410,18 +410,25 @@ static void sctp_intl_store_ordered(struct sctp_ulpq 
*ulpq,
                return;
        }
 
+       loc = NULL;
        skb_queue_walk(&ulpq->lobby, pos) {
                cevent = (struct sctp_ulpevent *)pos->cb;
 
-               if (cevent->stream > event->stream)
+               if (cevent->stream > event->stream) {
+                       loc = pos;
                        break;
-
+               }
                if (cevent->stream == event->stream &&
-                   MID_lt(event->mid, cevent->mid))
+                   MID_lt(event->mid, cevent->mid)) {
+                       loc = pos;
                        break;
+               }
        }
 
-       __skb_queue_before(&ulpq->lobby, pos, sctp_event2skb(event));
+       if (!loc)
+               __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
+       else
+               __skb_queue_before(&ulpq->lobby, loc, sctp_event2skb(event));
 }
 
 static void sctp_intl_retrieve_ordered(struct sctp_ulpq *ulpq,
-- 
2.19.1