[FFmpeg-devel] [PATCH 2/3] avcodec/osq: avoid several signed integer overflows

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: [FFmpeg-devel] [PATCH 2/3] avcodec/osq: avoid several signed integer overflows
Date: Tue, 26 Dec 2023 17:37:30 +0100
Message-ID: <20231226163731.4147-2-michael@niedermayer.cc> (raw)
In-Reply-To: <20231226163731.4147-1-michael@niedermayer.cc>

Fixes: signed integer overflow: 178459578 + 2009763270 cannot be represented in type 'int'
Fixes: 62285/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_OSQ_fuzzer-5013423686287360

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/osq.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/libavcodec/osq.c b/libavcodec/osq.c
index abe15c97f18..f2771c46eb5 100644
--- a/libavcodec/osq.c
+++ b/libavcodec/osq.c
@@ -222,8 +222,8 @@ static int osq_channel_parameters(AVCodecContext *avctx, int ch)
 #define C (-3)
 #define D (-4)
 #define E (-5)
-#define P2 ((dst[A] + dst[A]) - dst[B])
-#define P3 ((dst[A] - dst[B]) * 3 + dst[C])
+#define P2 (((unsigned)dst[A] + dst[A]) - dst[B])
+#define P3 (((unsigned)dst[A] - dst[B]) * 3 + dst[C])
 
 static int do_decode(AVCodecContext *avctx, AVFrame *frame, int decorrelate, int downsample)
 {
@@ -273,10 +273,10 @@ static int do_decode(AVCodecContext *avctx, AVFrame *frame, int decorrelate, int
             case 0:
                 break;
             case 1:
-                dst[n] += dst[A];
+                dst[n] += (unsigned)dst[A];
                 break;
             case 2:
-                dst[n] += dst[A] + p;
+                dst[n] += (unsigned)dst[A] + p;
                 break;
             case 3:
                 dst[n] += P2;
@@ -291,28 +291,28 @@ static int do_decode(AVCodecContext *avctx, AVFrame *frame, int decorrelate, int
                 dst[n] += P3 + p;
                 break;
             case 7:
-                dst[n] += (P2 + P3) / 2 + p;
+                dst[n] += (int)(P2 + P3) / 2 + (unsigned)p;
                 break;
             case 8:
-                dst[n] += (P2 + P3) / 2;
+                dst[n] += (int)(P2 + P3) / 2;
                 break;
             case 9:
-                dst[n] += (P2 * 2 + P3) / 3 + p;
+                dst[n] += (int)(P2 * 2 + P3) / 3 + (unsigned)p;
                 break;
             case 10:
-                dst[n] += (P2 + P3 * 2) / 3 + p;
+                dst[n] += (int)(P2 + P3 * 2) / 3 + (unsigned)p;
                 break;
             case 11:
-                dst[n] += (dst[A] + dst[B]) / 2;
+                dst[n] += (int)((unsigned)dst[A] + dst[B]) / 2;
                 break;
             case 12:
-                dst[n] += dst[B];
+                dst[n] += (unsigned)dst[B];
                 break;
             case 13:
-                dst[n] += (dst[D] + dst[B]) / 2;
+                dst[n] += (int)(unsigned)(dst[D] + dst[B]) / 2;
                 break;
             case 14:
-                dst[n] += (P2 + dst[A]) / 2 + p;
+                dst[n] += (int)((unsigned)P2 + dst[A]) / 2 + (unsigned)p;
                 break;
             default:
                 return AVERROR_INVALIDDATA;
-- 
2.17.1

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