SCTP: Fix the supported extensions paramter

Supported extensions parameter was not coded right and ended up
over-writing memory or causing skb overflows.  First, remove
the FWD_TSN support from as it shouldn't be there and also fix
the paramter encoding.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

1 files changed, 8 insertions, 15 deletions

diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c
index a139469792a3..f4876291bb5e 100644
--- a/net/sctp/sm_make_chunk.c
+++ b/net/sctp/sm_make_chunk.c
@@ -77,6 +77,8 @@ static int sctp_process_param(struct sctp_association *asoc,
                               union sctp_params param,
                               const union sctp_addr *peer_addr,
                               gfp_t gfp);
+static void *sctp_addto_param(struct sctp_chunk *chunk, int len,
+                              const void *data);
 
 /* What was the inbound interface for this chunk? */
 int sctp_chunk_iif(const struct sctp_chunk *chunk)
@@ -207,11 +209,7 @@ struct sctp_chunk *sctp_make_init(const struct sctp_association *asoc,
 
         chunksize = sizeof(init) + addrs_len + SCTP_SAT_LEN(num_types);
         chunksize += sizeof(ecap_param);
-        if (sctp_prsctp_enable) {
-                chunksize += sizeof(prsctp_param);
-                extensions[num_ext] = SCTP_CID_FWD_TSN;
-                num_ext += 1;
-        }
+
         /* ADDIP: Section 4.2.7:
          *  An implementation supporting this extension [ADDIP] MUST list
          *  the ASCONF,the ASCONF-ACK, and the AUTH  chunks in its INIT and
@@ -297,7 +295,7 @@ struct sctp_chunk *sctp_make_init(const struct sctp_association *asoc,
                             htons(sizeof(sctp_supported_ext_param_t) + num_ext);
                 sctp_addto_chunk(retval, sizeof(sctp_supported_ext_param_t),
                                 &ext_param);
-                sctp_addto_chunk(retval, num_ext, extensions);
+                sctp_addto_param(retval, num_ext, extensions);
         }
 
         if (sctp_prsctp_enable)
@@ -371,20 +369,12 @@ struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *asoc,
         if (asoc->peer.ecn_capable)
                 chunksize += sizeof(ecap_param);
 
-        /* Tell peer that we'll do PR-SCTP only if peer advertised.  */
-        if (asoc->peer.prsctp_capable) {
-                chunksize += sizeof(prsctp_param);
-                extensions[num_ext] = SCTP_CID_FWD_TSN;
-                num_ext += 1;
-        }
-
         if (sctp_addip_enable) {
                 extensions[num_ext] = SCTP_CID_ASCONF;
                 extensions[num_ext+1] = SCTP_CID_ASCONF_ACK;
                 num_ext += 2;
         }
 
-        chunksize += sizeof(ext_param) + num_ext;
         chunksize += sizeof(aiparam);
 
         if (asoc->peer.auth_capable) {
@@ -407,6 +397,9 @@ struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *asoc,
                 num_ext += 1;
         }
 
+        if (num_ext)
+                chunksize += sizeof(sctp_supported_ext_param_t) + num_ext;
+
         /* Now allocate and fill out the chunk.  */
         retval = sctp_make_chunk(asoc, SCTP_CID_INIT_ACK, 0, chunksize);
         if (!retval)
@@ -428,7 +421,7 @@ struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *asoc,
                             htons(sizeof(sctp_supported_ext_param_t) + num_ext);
                 sctp_addto_chunk(retval, sizeof(sctp_supported_ext_param_t),
                                  &ext_param);
-                sctp_addto_chunk(retval, num_ext, extensions);
+                sctp_addto_param(retval, num_ext, extensions);
         }
         if (asoc->peer.prsctp_capable)
                 sctp_addto_chunk(retval, sizeof(prsctp_param), &prsctp_param);