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

webrtc/api/webrtcsdp.cc

Index: webrtc/api/webrtcsdp.cc
diff --git a/webrtc/api/webrtcsdp.cc b/webrtc/api/webrtcsdp.cc
index 7238131cfe9111afa730f1951b682ee3f0b17a3d..4df4ef8566f355c7730962543fceac55ba8d7fab 100644
--- a/webrtc/api/webrtcsdp.cc
+++ b/webrtc/api/webrtcsdp.cc
@@ -2651,6 +2651,11 @@ bool ParseContent(const std::string& message,
         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;