[FFmpeg-devel] [PR] avcodec/jpeg2000htdec: Check Lcup and Lref (PR #21677)

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

PR #21677 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21677
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21677.patch

Fixes: use of uninitialized memory
Fixes: 482494999/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_DEC_fuzzer-6467586186608640

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


>From ce998935e801f9dcee7cca4ed71bf856b2153524 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Sat, 7 Feb 2026 22:55:11 +0100
Subject: [PATCH] avcodec/jpeg2000htdec: Check Lcup and Lref

Fixes: use of uninitialized memory
Fixes: 482494999/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_JPEG2000_DEC_fuzzer-6467586186608640

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/jpeg2000htdec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/jpeg2000htdec.c b/libavcodec/jpeg2000htdec.c
index b92f0131a4..3f5ed1ce22 100644
--- a/libavcodec/jpeg2000htdec.c
+++ b/libavcodec/jpeg2000htdec.c
@@ -1254,6 +1254,9 @@ ff_jpeg2000_decode_htj2k(const Jpeg2000DecoderContext *s, Jpeg2000CodingStyle *c
                "Cleanup pass length must be at least 2 bytes in length\n");
         return AVERROR_INVALIDDATA;
     }
+    if (Lcup + Lref != cblk->length)
+        return AVERROR_INVALIDDATA;
+
     Dcup = cblk->data;
     Dref  = cblk->data + Lcup; // Dref comes after the refinement segment
 
-- 
2.52.0

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