[FFmpeg-devel] [PR] avcodec/prores_raw: Tiles of width less than 16 result in undefined behavior (PR #21742)

[FFmpeg-devel] [PR] avcodec/prores_raw: Tiles of width less than 16 result in undefined behavior (PR #21742)

[michaelni via ffmpeg-devel]

PR #21742 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21742
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21742.patch

Fixes: passing zero to __builtin_clz(), which is not a valid argument
Fixes: 471569982/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PRORES_RAW_DEC_fuzzer-5832576221904896

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>


>From 40fb893468b8bf2076f3687714f7586eb4ae77c1 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Fri, 13 Feb 2026 00:06:26 +0100
Subject: [PATCH] avcodec/prores_raw: Tiles of width less than 16 result in
 undefined behavior

Fixes: passing zero to __builtin_clz(), which is not a valid argument
Fixes: 471569982/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PRORES_RAW_DEC_fuzzer-5832576221904896

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/prores_raw.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/prores_raw.c b/libavcodec/prores_raw.c
index eb1a9af14f..d852d40d64 100644
--- a/libavcodec/prores_raw.c
+++ b/libavcodec/prores_raw.c
@@ -251,6 +251,8 @@ static int decode_tile(AVCodecContext *avctx, TileContext *tile,
 
     if (tile->x >= avctx->width)
         return 0;
+    if (avctx->width - tile->x < 16)
+        return AVERROR_PATCHWELCOME;
 
     /* Tile header */
     int header_len = bytestream2_get_byteu(gb) >> 3;
-- 
2.52.0

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