From 36ad2f41e30ad9f2a8ead76e0b1526b9712f0925 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 31 Jan 2021 21:22:11 +0100 Subject: [PATCH] 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 --- libavcodec/ffv1dec.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c index 0a3f425493..8516fef5d7 100644 --- a/libavcodec/ffv1dec.c +++ b/libavcodec/ffv1dec.c @@ -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);