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avcodec/xvididct: Make c* unsigned to avoid undefined overflows 

Fixes: signed integer overflow: 1496950099 + 728014168 cannot be represented in type 'int'
Fixes: 62667/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MJPEGB_fuzzer-6511785170305024

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2023-10-05 18:27:28 +02:00
parent 61b86add52
commit f7e5537dc1
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GPG Key ID: B18E8928B3948D64
1 changed files with 9 additions and 9 deletions
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18
libavcodec/xvididct.c
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@ -56,13 +56,13 @@ static const int TAB35[] = { 26722, 25172, 22654, 19266, 15137, 10426, 5315 };
static int idct_row(short *in, const int *const tab, int rnd) static int idct_row(short *in, const int *const tab, int rnd)
{ {
const int c1 = tab[0]; const unsigned c1 = tab[0];
const int c2 = tab[1]; const unsigned c2 = tab[1];
const int c3 = tab[2]; const unsigned c3 = tab[2];
const int c4 = tab[3]; const unsigned c4 = tab[3];
const int c5 = tab[4]; const unsigned c5 = tab[4];
const int c6 = tab[5]; const unsigned c6 = tab[5];
const int c7 = tab[6]; const unsigned c7 = tab[6];
const int right = in[5] | in[6] | in[7]; const int right = in[5] | in[6] | in[7];
const int left = in[1] | in[2] | in[3]; const int left = in[1] | in[2] | in[3];
@ -102,8 +102,8 @@ static int idct_row(short *in, const int *const tab, int rnd)
return 0; return 0;
} }
} else if (!(left | right)) { } else if (!(left | right)) {
const int a0 = (rnd + c4 * (in[0] + in[4])) >> ROW_SHIFT; const int a0 = (int)(rnd + c4 * (in[0] + in[4])) >> ROW_SHIFT;
const int a1 = (rnd + c4 * (in[0] - in[4])) >> ROW_SHIFT; const int a1 = (int)(rnd + c4 * (in[0] - in[4])) >> ROW_SHIFT;
in[0] = a0; in[0] = a0;
in[3] = a0; in[3] = a0;