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avcodec/mpeg4videodec: Improve the overflow checks in mpeg4_decode_sprite_trajectory()

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Also clear the state on errors

Fixes integer overflows in 701/clusterfuzz-testcase-6594719951880192

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2017-03-02 03:02:07 +01:00
parent 2ce4f28431
commit eb41956636
1 changed files with 11 additions and 5 deletions
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16
libavcodec/mpeg4videodec.c
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@ -375,7 +375,7 @@ static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *g
FFABS(s->sprite_offset[1][1]) >= INT_MAX >> shift_c
) {
avpriv_request_sample(s->avctx, "Too large sprite shift or offset");
return AVERROR_PATCHWELCOME;
goto overflow;
}
for (i = 0; i < 2; i++) {
@ -385,17 +385,23 @@ static int mpeg4_decode_sprite_trajectory(Mpeg4DecContext *ctx, GetBitContext *g
s->sprite_delta[1][i] *= 1 << shift_y;
ctx->sprite_shift[i] = 16;
if (llabs(s->sprite_offset[i][0] + s->sprite_delta[i][0] * (int64_t)w) >= INT_MAX ||
llabs(s->sprite_offset[i][0] + s->sprite_delta[i][1] * (int64_t)h) >= INT_MAX ||
llabs(s->sprite_offset[i][0] + s->sprite_delta[i][0] * (int64_t)w + s->sprite_delta[i][1] * (int64_t)h) >= INT_MAX) {
}
for (i = 0; i < 2; i++) {
if (llabs(s->sprite_offset[0][i] + s->sprite_delta[i][0] * (w+16LL)) >= INT_MAX ||
llabs(s->sprite_offset[0][i] + s->sprite_delta[i][1] * (h+16LL)) >= INT_MAX ||
llabs(s->sprite_offset[0][i] + s->sprite_delta[i][0] * (w+16LL) + s->sprite_delta[i][1] * (h+16LL)) >= INT_MAX) {
avpriv_request_sample(s->avctx, "Overflow on sprite points");
return AVERROR_PATCHWELCOME;
goto overflow;
}
}
s->real_sprite_warping_points = ctx->num_sprite_warping_points;
}
return 0;
overflow:
memset(s->sprite_offset, 0, sizeof(s->sprite_offset));
memset(s->sprite_delta, 0, sizeof(s->sprite_delta));
return AVERROR_PATCHWELCOME;
}
static int decode_new_pred(Mpeg4DecContext *ctx, GetBitContext *gb) {