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mmvideo: fix overreads of the input buffer. 

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-03-04 08:14:07 +01:00
parent 999d38f3a9
commit 37fca5daa0
1 changed files with 16 additions and 4 deletions
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20
libavcodec/mmvideo.c
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@ -123,11 +123,18 @@ static void mm_decode_intra(MmContext * s, int half_horiz, int half_vert, const
*/
static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const uint8_t *buf, int buf_size)
{
const int data_ptr = 2 + AV_RL16(&buf[0]);
int data_ptr;
int d, r, y;
if(buf_size < 2) {
av_log(s->avctx, AV_LOG_ERROR, "1 or less byte inter frame\n");
return;
}
data_ptr = 2 + AV_RL16(&buf[0]);
d = data_ptr; r = 2; y = 0;
while(r < data_ptr) {
while(r + 1 < data_ptr) {
int i, j;
int length = buf[r] & 0x7f;
int x = buf[r+1] + ((buf[r] & 0x80) << 1);
@ -138,14 +145,19 @@ static void mm_decode_inter(MmContext * s, int half_horiz, int half_vert, const
continue;
}
if (y + half_vert >= s->avctx->height)
if (y + half_vert >= s->avctx->height || r+length > buf_size)
return;
for(i=0; i<length; i++) {
for(j=0; j<8; j++) {
int replace = (buf[r+i] >> (7-j)) & 1;
if (replace) {
int color = buf[d];
int color;
if (d >= buf_size) {
av_log(s->avctx, AV_LOG_ERROR, "overread buf\n");
return;
}
color = buf[d];
s->frame.data[0][y*s->frame.linesize[0] + x] = color;
if (half_horiz)
s->frame.data[0][y*s->frame.linesize[0] + x + 1] = color;