[FFmpeg-devel] [PATCH 2/4] avcodec/vmixdec: Check shift before use

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 2/4] avcodec/vmixdec: Check shift before use
Date: Wed, 20 Mar 2024 03:59:21 +0100
Message-ID: <20240320025923.3794-2-michael@niedermayer.cc> (raw)
In-Reply-To: <20240320025923.3794-1-michael@niedermayer.cc>

Fixes: shift exponent 32 is too large for 32-bit type 'unsigned int'
Fixes: 65909/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VMIX_fuzzer-519459745831321

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

diff --git a/libavcodec/vmixdec.c b/libavcodec/vmixdec.c
index d6b6e3557f..ab283d13db 100644
--- a/libavcodec/vmixdec.c
+++ b/libavcodec/vmixdec.c
@@ -235,6 +235,9 @@ static int decode_frame(AVCodecContext *avctx,
     else if (offset != 3)
         return AVERROR_INVALIDDATA;
 
+    if (s->lshift > 31)
+        return AVERROR_INVALIDDATA;
+
     q = quality[FFMIN(avpkt->data[offset - 2], FF_ARRAY_ELEMS(quality)-1)];
     for (int n = 0; n < 64; n++)
         s->factors[n] = quant[n] * q;
-- 
2.17.1

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