1 files changed, 27 insertions, 9 deletions

diff --git a/net/sctp/input.c b/net/sctp/input.c
index b24ff2c1aef5..238f1bffa684 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -305,18 +305,36 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
                            struct sctp_transport *t, __u32 pmtu)
 {
-        if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
-                printk(KERN_WARNING "%s: Reported pmtu %d too low, "
-                       "using default minimum of %d\n", __FUNCTION__, pmtu,
-                       SCTP_DEFAULT_MINSEGMENT);
-                pmtu = SCTP_DEFAULT_MINSEGMENT;
-        }
+        if (sock_owned_by_user(sk) || !t || (t->pathmtu == pmtu))
+                return;
 
-        if (!sock_owned_by_user(sk) && t && (t->pmtu != pmtu)) {
-                t->pmtu = pmtu;
+        if (t->param_flags & SPP_PMTUD_ENABLE) {
+                if (unlikely(pmtu < SCTP_DEFAULT_MINSEGMENT)) {
+                        printk(KERN_WARNING "%s: Reported pmtu %d too low, "
+                               "using default minimum of %d\n",
+                               __FUNCTION__, pmtu,
+                               SCTP_DEFAULT_MINSEGMENT);
+                        /* Use default minimum segment size and disable
+                         * pmtu discovery on this transport.
+                         */
+                        t->pathmtu = SCTP_DEFAULT_MINSEGMENT;
+                        t->param_flags = (t->param_flags & ~SPP_HB) |
+                                SPP_PMTUD_DISABLE;
+                } else {
+                        t->pathmtu = pmtu;
+                }
+
+                /* Update association pmtu. */
                 sctp_assoc_sync_pmtu(asoc);
-                sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
         }
+
+        /* 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.     
+         */
+        sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
 }
 
 /*