[FFmpeg-devel] [PATCH 6/6] avcodec/apedec: Use NABS to avoid undefined negation

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 6/6] avcodec/apedec: Use NABS to avoid undefined negation
Date: Mon,  1 Apr 2024 22:56:07 +0200
Message-ID: <20240401205607.9093-6-michael@niedermayer.cc> (raw)
In-Reply-To: <20240401205607.9093-1-michael@niedermayer.cc>

Fixes: negation of -2147483648 cannot be represented in type 'int32_t' (aka 'int'); cast to an unsigned type to negate this value to itself
Fixes: 67738/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APE_fuzzer-5444313212321792

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

diff --git a/libavcodec/apedec.c b/libavcodec/apedec.c
index 86b79182a73..d75a85f4664 100644
--- a/libavcodec/apedec.c
+++ b/libavcodec/apedec.c
@@ -1287,7 +1287,7 @@ static void predictor_decode_stereo_3950(APEContext *ctx, int count)
                 int32_t left  = a1 - (unsigned)(a0 / 2);
                 int32_t right = left + (unsigned)a0;
 
-                if (FFMAX(FFABS(left), FFABS(right)) > (1<<23)) {
+                if (FFMIN(FFNABS(left), FFNABS(right)) < -(1<<23)) {
                     ctx->interim_mode = !interim_mode;
                     av_log(ctx->avctx, AV_LOG_VERBOSE, "Interim mode: %d\n", ctx->interim_mode);
                     break;
-- 
2.17.1

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