mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-02 03:06:28 +02:00
a4405cc0cc
The DVD subtitle parser handles two types of packets: "normal" packets with a 16-bit length, and HD-DVD packets that set the 16-bit length to 0 and encode a 32-bit length in the next four bytes. This implies that HD-DVD packets are at least six bytes long, but the code didn't actually verify this. The faulty length check results in an out of bounds read for zero-length "normal" packets that occur in the input, which are only 2 bytes long, but get misinterpreted as an HD-DVD packet. When this happens the parser reads packet_len from beyond the end of the input buffer. The subtitle stream is not correctly decoded after this point due to the garbage packet_len. Fixing this is pretty simple: fix the length check so packets less than 6 bytes long will not be mistakenly parsed as HD-DVD packets. Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com> Signed-off-by: Anton Khirnov <anton@khirnov.net>
93 lines
3.0 KiB
C
93 lines
3.0 KiB
C
/*
|
|
* DVD subtitle decoding
|
|
* Copyright (c) 2005 Fabrice Bellard
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include <string.h>
|
|
|
|
#include "libavutil/intreadwrite.h"
|
|
#include "libavutil/mem.h"
|
|
#include "avcodec.h"
|
|
|
|
/* parser definition */
|
|
typedef struct DVDSubParseContext {
|
|
uint8_t *packet;
|
|
int packet_len;
|
|
int packet_index;
|
|
} DVDSubParseContext;
|
|
|
|
static int dvdsub_parse(AVCodecParserContext *s,
|
|
AVCodecContext *avctx,
|
|
const uint8_t **poutbuf, int *poutbuf_size,
|
|
const uint8_t *buf, int buf_size)
|
|
{
|
|
DVDSubParseContext *pc = s->priv_data;
|
|
|
|
*poutbuf = buf;
|
|
*poutbuf_size = buf_size;
|
|
|
|
if (pc->packet_index == 0) {
|
|
if (buf_size < 2 || (AV_RB16(buf) == 0 && buf_size < 6)) {
|
|
if (buf_size)
|
|
av_log(avctx, AV_LOG_DEBUG, "Parser input %d too small\n", buf_size);
|
|
return buf_size;
|
|
}
|
|
pc->packet_len = AV_RB16(buf);
|
|
if (pc->packet_len == 0) /* HD-DVD subpicture packet */
|
|
pc->packet_len = AV_RB32(buf+2);
|
|
av_freep(&pc->packet);
|
|
if ((unsigned)pc->packet_len > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE) {
|
|
av_log(avctx, AV_LOG_ERROR, "packet length %d is invalid\n", pc->packet_len);
|
|
return buf_size;
|
|
}
|
|
pc->packet = av_malloc(pc->packet_len + AV_INPUT_BUFFER_PADDING_SIZE);
|
|
}
|
|
if (pc->packet) {
|
|
if (pc->packet_index + buf_size <= pc->packet_len) {
|
|
memcpy(pc->packet + pc->packet_index, buf, buf_size);
|
|
pc->packet_index += buf_size;
|
|
if (pc->packet_index >= pc->packet_len) {
|
|
*poutbuf = pc->packet;
|
|
*poutbuf_size = pc->packet_len;
|
|
pc->packet_index = 0;
|
|
return buf_size;
|
|
}
|
|
} else {
|
|
/* erroneous size */
|
|
pc->packet_index = 0;
|
|
}
|
|
}
|
|
*poutbuf = NULL;
|
|
*poutbuf_size = 0;
|
|
return buf_size;
|
|
}
|
|
|
|
static av_cold void dvdsub_parse_close(AVCodecParserContext *s)
|
|
{
|
|
DVDSubParseContext *pc = s->priv_data;
|
|
av_freep(&pc->packet);
|
|
}
|
|
|
|
const AVCodecParser ff_dvdsub_parser = {
|
|
.codec_ids = { AV_CODEC_ID_DVD_SUBTITLE },
|
|
.priv_data_size = sizeof(DVDSubParseContext),
|
|
.parser_parse = dvdsub_parse,
|
|
.parser_close = dvdsub_parse_close,
|
|
};
|