From f2a0bde8f3008a737f22cce80656cfddc79fdbe6 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 8 Dec 2019 19:37:46 +0100 Subject: [PATCH] avcodec/vc1dec: Limit bits by the actual bitstream size Fixes: Timeout (350 ->19sec) Fixes: 19249/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-6566896438870016 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer (cherry picked from commit c56a52a82c0a4039e606e82b948a8abfe417f35f) Signed-off-by: Michael Niedermayer --- libavcodec/vc1dec.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c index fcc482e7eb..7f62099626 100644 --- a/libavcodec/vc1dec.c +++ b/libavcodec/vc1dec.c @@ -1033,7 +1033,7 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data, ff_mpeg_er_frame_start(s); - v->bits = buf_size * 8; + v->bits = FFMIN(buf_size * 8, s->gb.size_in_bits); v->end_mb_x = s->mb_width; if (v->field_mode) { s->current_picture.f->linesize[0] <<= 1; @@ -1107,8 +1107,10 @@ static int vc1_decode_frame(AVCodecContext *avctx, void *data, continue; } ff_vc1_decode_blocks(v); - if (i != n_slices) + if (i != n_slices) { s->gb = slices[i].gb; + v->bits = FFMIN(buf_size * 8, s->gb.size_in_bits); + } } if (v->field_mode) { v->second_field = 0;