From: Andreas Cadhalpun Date: Sun, 3 May 2015 18:36:20 +0000 (+0200) Subject: pngdec: don't use AV_PIX_FMT_MONOBLACK for apng X-Git-Tag: n2.7~731 X-Git-Url: http://git.videolan.org/?p=ffmpeg.git;a=commitdiff_plain;h=372aa0777aaacf726de7cd7dd0e6797026a124ee;ds=sidebyside 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 Signed-off-by: Michael Niedermayer --- diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c index 324f4e6ab7..1f8a77b37b 100644 --- a/libavcodec/pngdec.c +++ b/libavcodec/pngdec.c @@ -618,7 +618,7 @@ static int decode_idat_chunk(AVCodecContext *avctx, PNGDecContext *s, } else if ((s->bits_per_pixel == 1 || s->bits_per_pixel == 2 || s->bits_per_pixel == 4 || s->bits_per_pixel == 8) && s->color_type == PNG_COLOR_TYPE_PALETTE) { avctx->pix_fmt = AV_PIX_FMT_PAL8; - } else if (s->bit_depth == 1 && s->bits_per_pixel == 1) { + } else if (s->bit_depth == 1 && s->bits_per_pixel == 1 && avctx->codec_id != AV_CODEC_ID_APNG) { avctx->pix_fmt = AV_PIX_FMT_MONOBLACK; } else if (s->bit_depth == 8 && s->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {