[FFmpeg-devel] [PR] avcodec/flashsv: Check for input space before (re)allocating frame (PR #21706)

[FFmpeg-devel] [PR] avcodec/flashsv: Check for input space before (re)allocating frame (PR #21706)

[michaelni via ffmpeg-devel]

PR #21706 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21706
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21706.patch

Fixes: Timeout
Fixes: 471605680/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLASHSV2_DEC_fuzzer-6210773459468288
Fixes: 471605920/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLASHSV_DEC_fuzzer-6230719287590912

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


>From 164e3ff9ef9cd8f550c0972d62822a055632897e Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Tue, 10 Feb 2026 02:37:58 +0100
Subject: [PATCH] avcodec/flashsv: Check for input space before (re)allocating
 frame

Fixes: Timeout
Fixes: 471605680/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLASHSV2_DEC_fuzzer-6210773459468288
Fixes: 471605920/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FLASHSV_DEC_fuzzer-6230719287590912

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/flashsv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/flashsv.c b/libavcodec/flashsv.c
index d27918c923..ba5c995006 100644
--- a/libavcodec/flashsv.c
+++ b/libavcodec/flashsv.c
@@ -314,6 +314,9 @@ static int flashsv_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
     v_blocks = s->image_height / s->block_height;
     v_part   = s->image_height % s->block_height;
 
+    if (h_blocks * v_blocks * 16 > get_bits_left(&gb))
+        return AVERROR_INVALIDDATA;
+
     /* the block size could change between frames, make sure the buffer
      * is large enough, if not, get a larger one */
     if (s->block_size < s->block_width * s->block_height) {
-- 
2.52.0

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