avformat/gifdec: make GIF_APP_EXT_LABEL parsing more robust

Fixes Ticket3021

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2013-10-04 22:56:02 +02:00
parent b611ea041d
commit e1f8184a1a

View File

@ -164,17 +164,27 @@ static int gif_read_ext(AVFormatContext *s)
if ((ret = avio_skip(pb, sb_size - 3)) < 0 ) if ((ret = avio_skip(pb, sb_size - 3)) < 0 )
return ret; return ret;
} else if (ext_label == GIF_APP_EXT_LABEL) { } else if (ext_label == GIF_APP_EXT_LABEL) {
uint8_t netscape_ext[sizeof(NETSCAPE_EXT_STR)-1 + 2]; uint8_t data[256];
if ((sb_size = avio_r8(pb)) != strlen(NETSCAPE_EXT_STR)) sb_size = avio_r8(pb);
return 0; ret = avio_read(pb, data, sb_size);
ret = avio_read(pb, netscape_ext, sizeof(netscape_ext)); if (ret < 0 || !sb_size)
if (ret < sizeof(netscape_ext))
return ret; return ret;
gdc->total_iter = avio_rl16(pb);
if (sb_size == strlen(NETSCAPE_EXT_STR)) {
sb_size = avio_r8(pb);
ret = avio_read(pb, data, sb_size);
if (ret < 0 || !sb_size)
return ret;
if (sb_size == 3 && data[0] == 1) {
gdc->total_iter = AV_RL16(data+1);
if (gdc->total_iter == 0) if (gdc->total_iter == 0)
gdc->total_iter = -1; gdc->total_iter = -1;
} }
}
}
if ((ret = gif_skip_subblocks(pb)) < 0) if ((ret = gif_skip_subblocks(pb)) < 0)
return ret; return ret;