PR #25731 opened by DeVshaurya01 URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25731 Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25731.patch
av_get_packet() sets pkt->pos to the chunk payload, 8 bytes past the ANMF header. With AVFMT_GENERIC_INDEX and no read_seek, seeking goes there and the next read parses frame data as a chunk header, so every seek ends in EOF and ffmpeg -ss outputs nothing. Found-by: CS5187 grammar-aware seek-oracle fuzzer Signed-off-by: Shaurya Atram <[email protected]> # Summary of changes Briefly describe what this PR does and why. <!-- If this PR requires new FATE test samples, attach them to the PR and list their target paths below (relative to the fate-suite root). Attached filenames must match the sample's filename: ```fate-samples # e.g. vorbis/new-sample.ogg ``` --> >From ce836919d3b6377637827ff62cd44ea8bc416c23 Mon Sep 17 00:00:00 2001 From: Shaurya Atram <[email protected]> Date: Tue, 3 Nov 2026 15:15:28 +0000 Subject: [PATCH] avformat/webp_anim_dec: set packet pos to the ANMF chunk start av_get_packet() sets pkt->pos to the chunk payload, 8 bytes past the ANMF header. With AVFMT_GENERIC_INDEX and no read_seek, seeking goes there and the next read parses frame data as a chunk header, so every seek ends in EOF and ffmpeg -ss outputs nothing. Found-by: CS5187 grammar-aware seek-oracle fuzzer Signed-off-by: Shaurya Atram <[email protected]> --- libavformat/webp_anim_dec.c | 1 + 1 file changed, 1 insertion(+) diff --git a/libavformat/webp_anim_dec.c b/libavformat/webp_anim_dec.c index 14abb61db45..e81deea6c81 100644 --- a/libavformat/webp_anim_dec.c +++ b/libavformat/webp_anim_dec.c @@ -272,6 +272,7 @@ static int webp_anim_read_packet(AVFormatContext *s, AVPacket *pkt) ret = av_get_packet(pb, pkt, size); if (ret < 0) return ret; + pkt->pos = offset; if (!ctx->cur_frame++) pkt->flags |= AV_PKT_FLAG_KEY; pkt->pts = AV_NOPTS_VALUE; -- 2.54.0 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
