[SCTP]: Fix panic's when receiving fragmented SCTP control chunks.

Use pskb_pull() to handle incoming COOKIE_ECHO and HEARTBEAT chunks that
are received as skb's with fragment list.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index f5d131f52a70..8cdba51ec076 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -636,8 +636,9 @@ sctp_disposition_t sctp_sf_do_5_1D_ce(const struct sctp_endpoint *ep,
          */
         chunk->subh.cookie_hdr =
                 (struct sctp_signed_cookie *)chunk->skb->data;
-        skb_pull(chunk->skb,
-                 ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t));
+        if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
+                                         sizeof(sctp_chunkhdr_t)))
+                goto nomem;
 
         /* 5.1 D) Upon reception of the COOKIE ECHO chunk, Endpoint
          * "Z" will reply with a COOKIE ACK chunk after building a TCB
@@ -965,7 +966,8 @@ sctp_disposition_t sctp_sf_beat_8_3(const struct sctp_endpoint *ep,
          */
         chunk->subh.hb_hdr = (sctp_heartbeathdr_t *) chunk->skb->data;
         paylen = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t);
-        skb_pull(chunk->skb, paylen);
+        if (!pskb_pull(chunk->skb, paylen))
+                goto nomem;
 
         reply = sctp_make_heartbeat_ack(asoc, chunk,
                                         chunk->subh.hb_hdr, paylen);
@@ -1860,8 +1862,9 @@ sctp_disposition_t sctp_sf_do_5_2_4_dupcook(const struct sctp_endpoint *ep,
          * are in good shape.
          */
         chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data;
-        skb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
-                 sizeof(sctp_chunkhdr_t));
+        if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
+                                        sizeof(sctp_chunkhdr_t)))
+                goto nomem;
 
         /* In RFC 2960 5.2.4 3, if both Verification Tags in the State Cookie
          * of a duplicate COOKIE ECHO match the Verification Tags of the