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avcodec/dvdsubdec: fix out of bounds accesses

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The code blindly trusted buffer offsets read from the file in the RLE
decoder. Explicitly check the offset. Also error out on other RLE
decoding errors.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
wm4 2015-01-05 04:45:26 +01:00 committed by Michael Niedermayer
parent beedeb4399
commit c9151de7c4
1 changed files with 9 additions and 4 deletions
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13
libavcodec/dvdsubdec.c
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@ -108,6 +108,9 @@ static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
int x, y, len, color;
uint8_t *d;
if (start >= buf_size)
return -1;
bit_len = (buf_size - start) * 8;
init_get_bits(&gb, buf + start, bit_len);
@ -359,10 +362,12 @@ static int decode_dvd_subtitles(DVDSubContext *ctx, AVSubtitle *sub_header,
sub_header->rects[0] = av_mallocz(sizeof(AVSubtitleRect));
sub_header->num_rects = 1;
sub_header->rects[0]->pict.data[0] = bitmap;
decode_rle(bitmap, w * 2, w, (h + 1) / 2,
buf, offset1, buf_size, is_8bit);
decode_rle(bitmap + w, w * 2, w, h / 2,
buf, offset2, buf_size, is_8bit);
if (decode_rle(bitmap, w * 2, w, (h + 1) / 2,
buf, offset1, buf_size, is_8bit) < 0)
goto fail;
if (decode_rle(bitmap + w, w * 2, w, h / 2,
buf, offset2, buf_size, is_8bit) < 0)
goto fail;
sub_header->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
if (is_8bit) {
if (!yuv_palette)