Fixing heap read overflow when "sctp-port" is in a video description.

webrtc/api/webrtcsdp.cc

 /*
  *  Copyright 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 2633 matching lines @@
 
       if (!ParseFingerprintAttribute(line, &fingerprint, error)) {
         return false;
       }
       transport->identity_fingerprint.reset(fingerprint);
     } else if (HasAttribute(line, kAttributeSetup)) {
       if (!ParseDtlsSetup(line, &(transport->connection_role), error)) {
         return false;
       }
     } else if (IsDtlsSctp(protocol) && HasAttribute(line, kAttributeSctpPort)) {
+      if (media_type != cricket::MEDIA_TYPE_DATA) {
+        return ParseFailed(
+            line, "sctp-port attribute found in non-data media description.",
+            error);
+      }
       int sctp_port;
       if (!ParseSctpPort(line, &sctp_port, error)) {
         return false;
       }
       if (!AddSctpDataCodec(static_cast<DataContentDescription*>(media_desc),
                             sctp_port)) {
         return false;
       }
     } else if (IsRtp(protocol)) {
       //
@@ skipping 513 matching lines @@
     UpdateCodec<AudioContentDescription, cricket::AudioCodec>(
         media_desc, payload_type, feedback_param);
   } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
     UpdateCodec<VideoContentDescription, cricket::VideoCodec>(
         media_desc, payload_type, feedback_param);
   }
   return true;
 }
 
 }  // namespace webrtc