[FFmpeg-devel] [PATCH 5/6] avcodec/bonk: Avoid undefined overflow in quant

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 5/6] avcodec/bonk: Avoid undefined overflow in quant
Date: Wed, 11 Jan 2023 21:42:20 +0100
Message-ID: <20230111204221.22550-5-michael@niedermayer.cc> (raw)
In-Reply-To: <20230111204221.22550-1-michael@niedermayer.cc>

Fixes: signed integer overflow: -2889074 * 2048 cannot be represented in type 'int'
Fixes: 51363/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-5660734784143360
Fixes: 48567/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-6617680050520064
Fixes: 48567/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BONK_fuzzer-6743951854141440

No check is done for the overflow as this was rejected in last review, see the ML

Note: the 2nd and 3rd testcase was assigned by ossfuzz to a unrelated theora issue (48567)

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

diff --git a/libavcodec/bonk.c b/libavcodec/bonk.c
index 5d736b1563..9e176d5477 100644
--- a/libavcodec/bonk.c
+++ b/libavcodec/bonk.c
@@ -356,7 +356,7 @@ static int bonk_decode(AVCodecContext *avctx, AVFrame *frame,
                 sample++;
             }
 
-            sample[0] = predictor_calc_error(s->k, state, s->n_taps, s->input_samples[i] * quant);
+            sample[0] = predictor_calc_error(s->k, state, s->n_taps, s->input_samples[i] * (unsigned)quant);
             sample++;
         }
 
-- 
2.17.1

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