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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 <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2020-10-28 20:11:54 +01:00
parent 437b7302b0
commit 27a99e2c7d
1 changed files with 6 additions and 6 deletions
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12
libavformat/vividas.c
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@ -28,6 +28,7 @@
* @sa http://wiki.multimedia.cx/index.php?title=Vividas_VIV * @sa http://wiki.multimedia.cx/index.php?title=Vividas_VIV
*/ */
#include "libavutil/avassert.h"
#include "libavutil/intreadwrite.h" #include "libavutil/intreadwrite.h"
#include "avio_internal.h" #include "avio_internal.h"
#include "avformat.h" #include "avformat.h"
@ -379,7 +380,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *
if (avio_tell(pb) < off) { if (avio_tell(pb) < off) {
int num_data; int num_data;
int xd_size = 0; int xd_size = 1;
int data_len[256]; int data_len[256];
int offset = 1; int offset = 1;
uint8_t *p; uint8_t *p;
@ -393,10 +394,10 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
} }
data_len[j] = len; 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) if (ret < 0)
return ret; return ret;
@ -405,9 +406,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *
for (j = 0; j < num_data - 1; j++) { for (j = 0; j < num_data - 1; j++) {
unsigned delta = av_xiphlacing(&p[offset], data_len[j]); unsigned delta = av_xiphlacing(&p[offset], data_len[j]);
if (delta > data_len[j]) { av_assert0(delta <= xd_size - offset);
return AVERROR_INVALIDDATA;
}
offset += delta; offset += delta;
} }
@ -418,6 +417,7 @@ static int track_header(VividasDemuxContext *viv, AVFormatContext *s, uint8_t *
av_freep(&st->codecpar->extradata); av_freep(&st->codecpar->extradata);
break; break;
} }
av_assert0(data_len[j] <= xd_size - offset);
offset += data_len[j]; offset += data_len[j];
} }