avcodec/ffv1dec: Check if trailer is available

Fixes: out of array read
Fixes: 29750/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-4808377272238080.fuzz

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 2021-01-31 21:22:11 +01:00
parent 312bcdbfc1
commit 36ad2f41e3
1 changed files with 4 additions and 2 deletions

View File

@ -888,8 +888,10 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
int trailer = 3 + 5*!!f->ec;
int v;
if (i || f->version > 2) v = AV_RB24(buf_p-trailer) + trailer;
else v = buf_p - c->bytestream_start;
if (i || f->version > 2) {
if (trailer > buf_p - buf) v = INT_MAX;
else v = AV_RB24(buf_p-trailer) + trailer;
} else v = buf_p - c->bytestream_start;
if (buf_p - c->bytestream_start < v) {
av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n");
ff_thread_report_progress(&f->picture, INT_MAX, 0);