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avcodec/zmbv: Check that the decompressed data size is correct

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This checks the value exactly for intra frames and checks it against a
minimum for inter frames as they can be variable.

Fixes: Timeout
Fixes: 10182/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ZMBV_fuzzer-6245951174344704

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2018-09-18 00:28:37 +02:00
parent 3d201b83cd
commit e33b28cc79
1 changed files with 14 additions and 0 deletions
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14
libavcodec/zmbv.c
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@ -409,6 +409,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
int zret = Z_OK; // Zlib return code
int len = buf_size;
int hi_ver, lo_ver, ret;
int expected_size;
/* parse header */
if (len < 1)
@ -510,6 +511,14 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
memset(c->prev, 0, avctx->width * avctx->height * (c->bpp / 8));
c->decode_intra= decode_intra;
}
if (c->flags & ZMBV_KEYFRAME) {
expected_size = avctx->width * avctx->height * (c->bpp / 8);
} else {
expected_size = (c->bx * c->by * 2 + 3) & ~3;
}
if (avctx->pix_fmt == AV_PIX_FMT_PAL8 &&
(c->flags & (ZMBV_DELTAPAL | ZMBV_KEYFRAME)))
expected_size += 768;
if (!c->decode_intra) {
av_log(avctx, AV_LOG_ERROR, "Error! Got no format or no keyframe!\n");
@ -539,6 +548,11 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
}
c->decomp_len = c->zstream.total_out;
}
if (expected_size > c->decomp_len ||
(c->flags & ZMBV_KEYFRAME) && expected_size < c->decomp_len) {
av_log(avctx, AV_LOG_ERROR, "decompressed size %d is incorrect, expected %d\n", c->decomp_len, expected_size);
return AVERROR_INVALIDDATA;
}
if (c->flags & ZMBV_KEYFRAME) {
frame->key_frame = 1;
frame->pict_type = AV_PICTURE_TYPE_I;