sdp: reject large number of channels

the maximum used in practice is multiopus with 6 or 8 channels. 24 is the maximum number of channels supported in the audio decoder. BUG=chromium:1265806 Change-Id: Iba8e3185a1f235b846fed9c154e66fb3983664ed Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/238980 Reviewed-by: Harald Alvestrand <[email protected]> Commit-Queue: Philipp Hancke <[email protected]> Cr-Commit-Position: refs/heads/main@{#35440}
davidliu · Nov 30, 2021 · d58ac5a · d58ac5a
1 parent 6c167d8
commit d58ac5a
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diff --git a/pc/webrtc_sdp.cc b/pc/webrtc_sdp.cc
@@ -257,6 +257,9 @@ static const char kDefaultSctpmapProtocol[] = "webrtc-datachannel";
 // types.
 const int kWildcardPayloadType = -1;
 
+// Maximum number of channels allowed.
+static const size_t kMaxNumberOfChannels = 24;
+
 struct SsrcInfo {
   uint32_t ssrc_id;
   std::string cname;
@@ -3628,6 +3631,10 @@ bool ParseRtpmapAttribute(const std::string& line,
         return false;
       }
     }
+    if (channels > kMaxNumberOfChannels) {
+      return ParseFailed(line, "At most 24 channels are supported.", error);
+    }
+
     AudioContentDescription* audio_desc = media_desc->as_audio();
     UpdateCodec(payload_type, encoding_name, clock_rate, 0, channels,
                 audio_desc);

diff --git a/pc/webrtc_sdp_unittest.cc b/pc/webrtc_sdp_unittest.cc
@@ -4694,3 +4694,15 @@ TEST_F(WebRtcSdpTest, IllegalMidCharacterValue) {
   Replace("a=mid:", "a=mid:[]", &sdp);
   ExpectParseFailure(std::string(sdp), "a=mid:[]");
 }
+
+TEST_F(WebRtcSdpTest, MaxChannels) {
+  std::string sdp =
+      "v=0\r\n"
+      "o=- 11 22 IN IP4 127.0.0.1\r\n"
+      "s=-\r\n"
+      "t=0 0\r\n"
+      "m=audio 49232 RTP/AVP 108\r\n"
+      "a=rtpmap:108 ISAC/16000/512\r\n";
+
+  ExpectParseFailure(sdp, "a=rtpmap:108 ISAC/16000/512");
+}