1 files changed, 15 insertions, 1 deletions

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index 910926906a3a..73bdeb2b6c62 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -2570,6 +2570,12 @@ sctp_disposition_t sctp_sf_do_9_2_shutdown(const struct sctp_endpoint *ep,
         chunk->subh.shutdown_hdr = sdh;
         ctsn = ntohl(sdh->cum_tsn_ack);
 
+        if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
+                SCTP_DEBUG_PRINTK("ctsn %x\n", ctsn);
+                SCTP_DEBUG_PRINTK("ctsn_ack_point %x\n", asoc->ctsn_ack_point);
+                return SCTP_DISPOSITION_DISCARD;
+        }
+
         /* If Cumulative TSN Ack beyond the max tsn currently
          * send, terminating the association and respond to the
          * sender with an ABORT.
@@ -2633,6 +2639,7 @@ sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(const struct sctp_endpoint *ep,
 {
         struct sctp_chunk *chunk = arg;
         sctp_shutdownhdr_t *sdh;
+        __u32 ctsn;
 
         if (!sctp_vtag_verify(chunk, asoc))
                 return sctp_sf_pdiscard(ep, asoc, type, arg, commands);
@@ -2644,12 +2651,19 @@ sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(const struct sctp_endpoint *ep,
                                                   commands);
 
         sdh = (sctp_shutdownhdr_t *)chunk->skb->data;
+        ctsn = ntohl(sdh->cum_tsn_ack);
+
+        if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
+                SCTP_DEBUG_PRINTK("ctsn %x\n", ctsn);
+                SCTP_DEBUG_PRINTK("ctsn_ack_point %x\n", asoc->ctsn_ack_point);
+                return SCTP_DISPOSITION_DISCARD;
+        }
 
         /* If Cumulative TSN Ack beyond the max tsn currently
          * send, terminating the association and respond to the
          * sender with an ABORT.
          */
-        if (!TSN_lt(ntohl(sdh->cum_tsn_ack), asoc->next_tsn))
+        if (!TSN_lt(ctsn, asoc->next_tsn))
                 return sctp_sf_violation_ctsn(ep, asoc, type, arg, commands);
 
         /* verify, by checking the Cumulative TSN Ack field of the