pngdec: don't use AV_PIX_FMT_MONOBLACK for apng
authorAndreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Sun, 3 May 2015 18:36:20 +0000 (20:36 +0200)
committerMichael Niedermayer <michaelni@gmx.at>
Sun, 3 May 2015 19:50:09 +0000 (21:50 +0200)
commit372aa0777aaacf726de7cd7dd0e6797026a124ee
treec52054e140138be54be5a5418d9ed0b9e38a6435
parent8f760be4d312bb6e78f80d39b9d0062253332e08
pngdec: don't use AV_PIX_FMT_MONOBLACK for apng

AV_PIX_FMT_MONOBLACK has the AV_PIX_FMT_FLAG_BITSTREAM flag, i.e.
linesize can be smaller than width.

Since x_offset is only check against the width, this can lead to
x_offset * bpp >= image_linesize.

In this case ptr could be set to a position outside the image_buf in
png_handle_row, leading to memory corruption and thus crashes.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
libavcodec/pngdec.c