1 files changed, 16 insertions, 12 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 621b5ca3fd1c..141c9c466ec1 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -399,20 +399,24 @@ void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
                 return;
         }
 
-        if (t->param_flags & SPP_PMTUD_ENABLE) {
-                /* Update transports view of the MTU */
-                sctp_transport_update_pmtu(t, pmtu);
-
-                /* Update association pmtu. */
-                sctp_assoc_sync_pmtu(asoc);
-        }
+        if (!(t->param_flags & SPP_PMTUD_ENABLE))
+                /* We can't allow retransmitting in such case, as the
+                 * retransmission would be sized just as before, and thus we
+                 * would get another icmp, and retransmit again.
+                 */
+                return;
 
-        /* Retransmit with the new pmtu setting.
-         * Normally, if PMTU discovery is disabled, an ICMP Fragmentation
-         * Needed will never be sent, but if a message was sent before
-         * PMTU discovery was disabled that was larger than the PMTU, it
-         * would not be fragmented, so it must be re-transmitted fragmented.
+        /* Update transports view of the MTU. Return if no update was needed.
+         * If an update wasn't needed/possible, it also doesn't make sense to
+         * try to retransmit now.
          */
+        if (!sctp_transport_update_pmtu(t, pmtu))
+                return;
+
+        /* Update association pmtu. */
+        sctp_assoc_sync_pmtu(asoc);
+
+        /* Retransmit with the new pmtu setting. */
         sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 }