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authorMichael Niedermayer <michael@niedermayer.cc>2020-05-02 21:25:17 +0200
committerMichael Niedermayer <michael@niedermayer.cc>2020-05-21 15:32:28 +0200
commit53bfdb6fdb3686e6b65e3f94704ab137af992d09 (patch)
treedec414787ad823f4ae47fdc5e067ef924aad7311
parent5df443f763e2c6f5046c5ab389b746c548904ef9 (diff)
downloadffmpeg-53bfdb6fdb3686e6b65e3f94704ab137af992d09.tar.gz
avcodec/xvididct: Fix integer overflow in idct_row()
Fixes: signed integer overflow: -1238335488 + -1003634688 cannot be represented in type 'int' Fixes: 21649/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MJPEG_fuzzer-5112005765890048 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer <michael@niedermayer.cc> (cherry picked from commit 620236e4d2ac46821911b99fa4551868675d4ed9) Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
-rw-r--r--libavcodec/xvididct.c36
1 files changed, 18 insertions, 18 deletions
diff --git a/libavcodec/xvididct.c b/libavcodec/xvididct.c
index 14116bd6d3..360deb3244 100644
--- a/libavcodec/xvididct.c
+++ b/libavcodec/xvididct.c
@@ -115,24 +115,24 @@ static int idct_row(short *in, const int *const tab, int rnd)
in[6] = a1;
} else {
const int k = c4 * in[0] + rnd;
- const int a0 = k + c2 * in[2] + c4 * in[4] + c6 * in[6];
- const int a1 = k + c6 * in[2] - c4 * in[4] - c2 * in[6];
- const int a2 = k - c6 * in[2] - c4 * in[4] + c2 * in[6];
- const int a3 = k - c2 * in[2] + c4 * in[4] - c6 * in[6];
-
- const int b0 = c1 * in[1] + c3 * in[3] + c5 * in[5] + c7 * in[7];
- const int b1 = c3 * in[1] - c7 * in[3] - c1 * in[5] - c5 * in[7];
- const int b2 = c5 * in[1] - c1 * in[3] + c7 * in[5] + c3 * in[7];
- const int b3 = c7 * in[1] - c5 * in[3] + c3 * in[5] - c1 * in[7];
-
- in[0] = (a0 + b0) >> ROW_SHIFT;
- in[1] = (a1 + b1) >> ROW_SHIFT;
- in[2] = (a2 + b2) >> ROW_SHIFT;
- in[3] = (a3 + b3) >> ROW_SHIFT;
- in[4] = (a3 - b3) >> ROW_SHIFT;
- in[5] = (a2 - b2) >> ROW_SHIFT;
- in[6] = (a1 - b1) >> ROW_SHIFT;
- in[7] = (a0 - b0) >> ROW_SHIFT;
+ const unsigned int a0 = k + c2 * in[2] + c4 * in[4] + c6 * in[6];
+ const unsigned int a1 = k + c6 * in[2] - c4 * in[4] - c2 * in[6];
+ const unsigned int a2 = k - c6 * in[2] - c4 * in[4] + c2 * in[6];
+ const unsigned int a3 = k - c2 * in[2] + c4 * in[4] - c6 * in[6];
+
+ const unsigned int b0 = c1 * in[1] + c3 * in[3] + c5 * in[5] + c7 * in[7];
+ const unsigned int b1 = c3 * in[1] - c7 * in[3] - c1 * in[5] - c5 * in[7];
+ const unsigned int b2 = c5 * in[1] - c1 * in[3] + c7 * in[5] + c3 * in[7];
+ const unsigned int b3 = c7 * in[1] - c5 * in[3] + c3 * in[5] - c1 * in[7];
+
+ in[0] = (int)(a0 + b0) >> ROW_SHIFT;
+ in[1] = (int)(a1 + b1) >> ROW_SHIFT;
+ in[2] = (int)(a2 + b2) >> ROW_SHIFT;
+ in[3] = (int)(a3 + b3) >> ROW_SHIFT;
+ in[4] = (int)(a3 - b3) >> ROW_SHIFT;
+ in[5] = (int)(a2 - b2) >> ROW_SHIFT;
+ in[6] = (int)(a1 - b1) >> ROW_SHIFT;
+ in[7] = (int)(a0 - b0) >> ROW_SHIFT;
}
return 1;
}