PR #22507 opened by npc URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/22507 Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/22507.patch
new_pes_packet() moves a buffer with pkt->buf = pes->buffer before JPEG-XS validation. If header_size > pkt->size, an early return leaves pes->buffer as a stale alias of pkt->buf with refcount 1. Later, mpegts_read_packet() calls av_packet_unref(), freeing the buffer through pkt->buf. The flush loop then re-enters new_pes_packet() and dereferences the dangling pes->buffer; a second path hits it via av_buffer_unref() in handle_packets() after a seek. Drop the early return. The packet is delivered with AV_PKT_FLAG_CORRUPT set, matching the PES-size-mismatch case above, and the function falls through to the normal cleanup path. The else guards the header trim so pkt->data/pkt->size stay valid for the memset. Fixes: use after free Fixes regression since 16f89d342e. Found-by: Nicholas Carlini <[email protected]> >From a654cfce71aa58b7da8d2855cbc0a53bb162f596 Mon Sep 17 00:00:00 2001 From: Nicholas Carlini <[email protected]> Date: Sat, 14 Mar 2026 15:39:51 +0000 Subject: [PATCH] avformat/mpegts: remove JPEG-XS early return on invalid header_size new_pes_packet() moves a buffer with pkt->buf = pes->buffer before JPEG-XS validation. If header_size > pkt->size, an early return leaves pes->buffer as a stale alias of pkt->buf with refcount 1. Later, mpegts_read_packet() calls av_packet_unref(), freeing the buffer through pkt->buf. The flush loop then re-enters new_pes_packet() and dereferences the dangling pes->buffer; a second path hits it via av_buffer_unref() in handle_packets() after a seek. Drop the early return. The packet is delivered with AV_PKT_FLAG_CORRUPT set, matching the PES-size-mismatch case above, and the function falls through to the normal cleanup path. The else guards the header trim so pkt->data/pkt->size stay valid for the memset. Fixes: use after free Fixes regression since 16f89d342e. Found-by: Nicholas Carlini <[email protected]> --- libavformat/mpegts.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c index 0ee10f9a77..bfbdbf5b19 100644 --- a/libavformat/mpegts.c +++ b/libavformat/mpegts.c @@ -1041,10 +1041,10 @@ static int new_pes_packet(PESContext *pes, AVPacket *pkt) "Invalid JPEG-XS header size %"PRIu32" > packet size %d\n", header_size, pkt->size); pes->flags |= AV_PKT_FLAG_CORRUPT; - return AVERROR_INVALIDDATA; + } else { + pkt->data += header_size; + pkt->size -= header_size; } - pkt->data += header_size; - pkt->size -= header_size; } memset(pkt->data + pkt->size, 0, AV_INPUT_BUFFER_PADDING_SIZE); -- 2.52.0 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
