[FFmpeg-devel] [PATCH] avcodec/jpeg2000dec: Make sure the 4 extra bytes allocated are initialized (PR #20195)

[FFmpeg-devel] [PATCH] avcodec/jpeg2000dec: Make sure the 4 extra bytes allocated are initialized (PR #20195)

[michaelni]

PR #20195 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20195
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20195.patch

Fixes: use of uninitialized memory
Fixes: 429130590/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_DEC_fuzzer-5736930522497024

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


From 2d67eb718e9d3088c0f575ace40f51e12b3f1acd Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Sat, 9 Aug 2025 11:38:07 +0200
Subject: [PATCH] avcodec/jpeg2000dec: Make sure the 4 extra bytes allocated
 are initialized

Fixes: use of uninitialized memory
Fixes: 429130590/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_DEC_fuzzer-5736930522497024

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/jpeg2000dec.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libavcodec/jpeg2000dec.c b/libavcodec/jpeg2000dec.c
index 59f3133d1f..221ba87305 100644
--- a/libavcodec/jpeg2000dec.c
+++ b/libavcodec/jpeg2000dec.c
@@ -1532,6 +1532,7 @@ static int jpeg2000_decode_packet(Jpeg2000DecoderContext *s, Jpeg2000Tile *tile,
 
                 bytestream2_get_bufferu(&s->g, cblk->data + cblk->length, cblk->lengthinc[cwsno]);
                 cblk->length   += cblk->lengthinc[cwsno];
+                memset(cblk->data + cblk->length, 0, 4);
                 cblk->lengthinc[cwsno] = 0;
                 if (cblk->nb_terminationsinc) {
                     cblk->nb_terminationsinc--;
-- 
2.49.1

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