Fix SIGSEGV in gst-kvs-plugin video-only pipeline when WebRTC is enabled#480
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narutaro wants to merge 1 commit intoaws-samples:masterfrom
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Fix SIGSEGV in gst-kvs-plugin video-only pipeline when WebRTC is enabled#480narutaro wants to merge 1 commit intoaws-samples:masterfrom
narutaro wants to merge 1 commit intoaws-samples:masterfrom
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When using kvsplugin with a video-only GStreamer pipeline (no audio pad) and connect-webrtc=true, the plugin crashes with SIGSEGV when a WebRTC viewer connects due to two NULL pointer dereferences: 1. createWebRtcStreamingSession(): audioContentType is NULL when no audio pad is connected, causing STRNCMP to segfault. Added NULL check and inactive audio transceiver fallback to maintain SDP m-line order. 2. handleOffer(): receiveGstreamerAudioVideo() thread unconditionally accesses pAudioRtcRtpTransceiver which is NULL without audio. Added NULL guard to skip thread creation.
sirknightj
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Mar 12, 2026
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Thank you for the contribution
| audioTrack.codec = RTC_CODEC_ALAW; | ||
| } else if (STRNCMP(pGstKvsPlugin->gstParams.audioContentType, AUDIO_OPUS_CONTENT_TYPE, MAX_GSTREAMER_MEDIA_TYPE_LEN) == 0) { | ||
| audioTrack.codec = RTC_CODEC_OPUS; | ||
| // [KVS-DUAL-STREAM-TEST] Skip audio transceiver if no audio content type (video-only pipeline) |
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Wondering what's up with the "dual stream test" prefix in some comments?
unicornss
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Mar 12, 2026
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Thanks for your contribution!
| STRCPY(audioTrack.trackId, "myAudioTrack"); | ||
| RtcRtpTransceiverInit transceiverInit; | ||
| transceiverInit.direction = RTC_RTP_TRANSCEIVER_DIRECTION_INACTIVE; | ||
| CHK_STATUS(addTransceiver(pStreamingSession->pPeerConnection, &audioTrack, &transceiverInit, &pStreamingSession->pAudioRtcRtpTransceiver)); |
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should it also have the transceiverOnBandwidthEstimation ?
| audioTrack.codec = RTC_CODEC_OPUS; | ||
| STRCPY(audioTrack.streamId, "myKvsVideoStream"); | ||
| STRCPY(audioTrack.trackId, "myAudioTrack"); | ||
| RtcRtpTransceiverInit transceiverInit; |
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RtcRtpTransceiverInit transceiverInit = {0}; // or memset?
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Problem
When using
kvspluginwith a video-only GStreamer pipeline (no audio pad) andconnect-webrtc=true, the plugin crashes with SIGSEGV when a WebRTC viewer connects.Two NULL pointer dereferences occur:
createWebRtcStreamingSession():pGstKvsPlugin->gstParams.audioContentTypeis NULL when no audio pad is connected. This NULL pointer is passed toSTRNCMP(), causing a segfault.handleOffer():receiveGstreamerAudioVideo()thread is unconditionally started, but accessespStreamingSession->pAudioRtcRtpTransceiverwhich is NULL when no audio transceiver was created.Additionally, simply skipping the audio transceiver causes the SDP answer m-line order to not match the offer, resulting in the viewer rejecting the answer.
Reproduce
Connect a viewer from the KVS WebRTC test page with
useTrickleICEenabled → SIGSEGV.Fix
Change 1: NULL check for audioContentType + inactive fallback transceiver
In
createWebRtcStreamingSession(), wrap the audio codec selection in a NULL check. WhenaudioContentTypeis NULL (video-only pipeline), add an inactive audio transceiver with Opus codec to maintain SDP m-line order compatibility with the viewer's offer.Change 2: Guard receiveGstreamerAudioVideo thread
In
handleOffer(), only start thereceiveGstreamerAudioVideothread whenpAudioRtcRtpTransceiveris not NULL.Testing
Tested on Ubuntu EC2 (x86_64) with WebRTC SDK v1.7.3:
enable-streaming=false)enable-streaming=true)