[FFmpeg-devel] [PATCH] avformat/mpegts: bounds-check JPEG-XS header_size before padding (PR #21196)

[ruikai via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #21196 opened by ruikai
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21196
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21196.patch

Regression since: 536475ea05.

The JPEG-XS PES path trusted header_size from the payload and advanced
pkt->data/pkt->size without validation, so the trailing memset could
write out of bounds when header_size > pkt->size. Reject such packets,
marking them corrupt and returning an error to avoid the OOB write.

Repro (ASan):
ASAN_OPTIONS=halt_on_error=1:detect_leaks=0 \
./ffmpeg -v debug -nostdin -i poc-jpegxs.ts -copy_unknown -map 0 \
 -c copy -f null /dev/null

Crash in new_pes_packet memset on crafted TS with stream_id 0xbd,
stream_type 0x32, header_size 0xFFFFFF00, payload starting with jxes.

Found-by: Pwno


>From 91385c6417b60d2d609bceb6ccab3da28070a263 Mon Sep 17 00:00:00 2001
From: Ruikai Peng <ruikai@pwno.io>
Date: Sun, 14 Dec 2025 12:26:37 -0500
Subject: [PATCH] avformat/mpegts: bounds-check JPEG-XS header_size before
 padding

Regression since: 536475ea05.

The JPEG-XS PES path trusted header_size from the payload and advanced
pkt->data/pkt->size without validation, so the trailing memset could
write out of bounds when header_size > pkt->size. Reject such packets,
marking them corrupt and returning an error to avoid the OOB write.

Repro (ASan):
ASAN_OPTIONS=halt_on_error=1:detect_leaks=0   ./ffmpeg -v debug -nostdin -i poc-jpegxs.ts -copy_unknown -map 0   -c copy -f null /dev/null

Crash in new_pes_packet memset on crafted TS with stream_id 0xbd,
stream_type 0x32, header_size 0xFFFFFF00, payload starting with jxes.

Found-by: Pwno
---
 libavformat/mpegts.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index fb1dcd11be..7c19abaf76 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -1035,6 +1035,13 @@ static int new_pes_packet(PESContext *pes, AVPacket *pkt)
         pkt->size >= 8 && memcmp(pkt->data + 4, "jxes", 4) == 0)
     {
         uint32_t header_size = AV_RB32(pkt->data);
+        if (header_size > pkt->size) {
+            av_log(pes->stream, AV_LOG_WARNING,
+                   "Invalid JPEG-XS header size %"PRIu32" > packet size %d\n",
+                   header_size, pkt->size);
+            pes->flags |= AV_PKT_FLAG_CORRUPT;
+            return AVERROR_INVALIDDATA;
+        }
         pkt->data += header_size;
         pkt->size -= header_size;
     }
-- 
2.49.1

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