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avcodec/sunrast: Fix maplength check 

Fixes: out of bounds read

Found-by: Ibrahim Mohamed <ielsayed@meta.com>
Reviewed-by; Ibrahim Mohamed <ielsayed@meta.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2022-12-21 00:31:00 +01:00
parent b92260f70a
commit f8a2a65078
No known key found for this signature in database
GPG Key ID: B18E8928B3948D64
1 changed files with 17 additions and 2 deletions
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19
libavcodec/sunrast.c
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@ -19,6 +19,7 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/avassert.h"
#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "avcodec.h"
@ -75,6 +76,12 @@ static int sunrast_decode_frame(AVCodecContext *avctx, AVFrame *p,
return AVERROR_PATCHWELCOME;
}
if (maplength > 768) {
av_log(avctx, AV_LOG_WARNING, "invalid colormap length\n");
return AVERROR_INVALIDDATA;
}
// This also checks depth to be valid
switch (depth) {
case 1:
avctx->pix_fmt = maplength ? AV_PIX_FMT_PAL8 : AV_PIX_FMT_MONOWHITE;
@ -96,15 +103,23 @@ static int sunrast_decode_frame(AVCodecContext *avctx, AVFrame *p,
return AVERROR_INVALIDDATA;
}
// This checks w and h to be valid in the sense that bytes of a padded bitmap are addressable with 32bit int
ret = ff_set_dimensions(avctx, w, h);
if (ret < 0)
return ret;
// ensured by ff_set_dimensions()
av_assert0(w <= (INT32_MAX - 7) / depth);
/* scanlines are aligned on 16 bit boundaries */
len = (depth * w + 7) >> 3;
alen = len + (len & 1);
if (buf_end - buf < maplength + (len * h) * 3 / 256)
// ensured by ff_set_dimensions()
av_assert0(h <= INT32_MAX / (3 * len));
// maplength is limited to 768 and the right term is limited to INT32_MAX / 256 so the add needs no check
if (buf_end - buf < (uint64_t)maplength + (len * h) * 3 / 256)
return AVERROR_INVALIDDATA;
if ((ret = ff_get_buffer(avctx, p, 0)) < 0)
@ -118,7 +133,7 @@ static int sunrast_decode_frame(AVCodecContext *avctx, AVFrame *p,
} else if (maplength) {
unsigned int len = maplength / 3;
if (maplength % 3 || maplength > 768) {
if (maplength % 3) {
av_log(avctx, AV_LOG_WARNING, "invalid colormap length\n");
return AVERROR_INVALIDDATA;
}