From 22c3cd176079dd104ec7610ead697235b04396f1 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Tue, 29 Sep 2020 10:21:34 +0200 Subject: [PATCH] avformat/movenc: Fix segfault when remuxing rtp hint stream When remuxing an rtp hint stream (or any stream with the tag "rtp "), the mov muxer treats this as one of the rtp hint tracks it creates internally when ordered to do so; yet this track lacks the AVFormatContext for the hinting rtp muxer, leading to segfaults in mov_write_udta_sdp() if a "trak" atom is written for this stream; if not, the stream's codecpar is freed by mov_free() as if the mov muxer owned it (it does for the internally created "rtp " tracks), but without resetting st->codecpar, leading to double-frees lateron. This commit therefore ignores said tag which makes rtp hint streams unremuxable. This fixes tickets #8181 and #8186. Signed-off-by: Andreas Rheinhardt --- libavformat/movenc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/libavformat/movenc.c b/libavformat/movenc.c index 6c641d549d..ae32b39dbb 100644 --- a/libavformat/movenc.c +++ b/libavformat/movenc.c @@ -1653,6 +1653,10 @@ static unsigned int mov_get_codec_tag(AVFormatContext *s, MOVTrack *track) { unsigned int tag = track->par->codec_tag; + // "rtp " is used to distinguish internally created RTP-hint tracks + // (with rtp_ctx) from other tracks. + if (tag == MKTAG('r','t','p',' ')) + tag = 0; if (!tag || (s->strict_std_compliance >= FF_COMPLIANCE_NORMAL && (track->par->codec_id == AV_CODEC_ID_DVVIDEO || track->par->codec_id == AV_CODEC_ID_RAWVIDEO ||