From 27a99e2c7d450fef15594671eef4465c8a166bd7 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Wed, 28 Oct 2020 20:11:54 +0100 Subject: [PATCH] avformat/vividas: improve extradata packing checks in track_header() Fixes: out of array accesses Fixes: 26622/clusterfuzz-testcase-minimized-ffmpeg_dem_VIVIDAS_fuzzer-6581200338288640 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer Upstream-Status: Backport [https://github.com/FFmpeg/FFmpeg/commit/27a99e2c7d450fef15594671eef4465c8a166bd7] CVE: CVE-2020-35964 Signed-off-by: Michael Niedermayer Signed-off-by: Khairul Rohaizzat Jamaluddin --- libavformat/vividas.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/libavformat/vividas.c b/libavformat/vividas.c index 83d0ed116787..46c66bf9a0ae 100644 --- a/libavformat/vividas.c +++ b/libavformat/vividas.c @@ -28,6 +28,7 @@ * @sa http://wiki.multimedia.cx/index.php?title=Vividas_VIV */ +#include "libavutil/avassert.h" #include "libavutil/intreadwrite.h" #include "avio_internal.h" #include "avformat.h" @@ -379,7 +380,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t * if (avio_tell(pb) < off) { int num_data; - int xd_size = 0; + int xd_size = 1; int data_len[256]; int offset = 1; uint8_t *p; @@ -393,10 +394,10 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t * return AVERROR_INVALIDDATA; } data_len[j] = len; - xd_size += len; + xd_size += len + 1 + len/255; } - ret = ff_alloc_extradata(st->codecpar, 64 + xd_size + xd_size / 255); + ret = ff_alloc_extradata(st->codecpar, xd_size); if (ret < 0) return ret; @@ -405,9 +406,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t * for (j = 0; j < num_data - 1; j++) { unsigned delta = av_xiphlacing(&p[offset], data_len[j]); - if (delta > data_len[j]) { - return AVERROR_INVALIDDATA; - } + av_assert0(delta <= xd_size - offset); offset += delta; } @@ -418,6 +417,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t * av_freep(&st->codecpar->extradata); break; } + av_assert0(data_len[j] <= xd_size - offset); offset += data_len[j]; }