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FFmpeg/libavcodec/cdtoons.c
Michael Niedermayer 4d701e9222 avcodec/cdtoons: Check sprite_offset is within the packet 
Fixes: out of array read
Fixes: 20659/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CDTOONS_fuzzer-5754518731227136

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2020-05-12 21:39:13 +02:00

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/*
* CDToons video decoder
* Copyright (C) 2020 Alyssa Milburn <amilburn@zall.org>
*
* 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
*/
/**
* @file
* CDToons video decoder
* @author Alyssa Milburn <amilburn@zall.org>
*/
#include <stdint.h>
#include "libavutil/attributes.h"
#include "libavutil/internal.h"
#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#define CDTOONS_HEADER_SIZE 44
#define CDTOONS_MAX_SPRITES 1200
typedef struct CDToonsSprite {
uint16_t flags;
uint16_t owner_frame;
uint16_t start_frame;
uint16_t end_frame;
unsigned int alloc_size;
uint32_t size;
uint8_t *data;
int active;
} CDToonsSprite;
typedef struct CDToonsContext {
AVFrame *frame;
uint16_t last_pal_id; ///< The index of the active palette sprite.
uint32_t pal[256]; ///< The currently-used palette data.
CDToonsSprite sprites[CDTOONS_MAX_SPRITES];
} CDToonsContext;
static int cdtoons_render_sprite(AVCodecContext *avctx, const uint8_t *data,
uint32_t data_size,
int dst_x, int dst_y, int width, int height)
{
CDToonsContext *c = avctx->priv_data;
const uint8_t *next_line = data;
const uint8_t *end = data + data_size;
uint16_t line_size;
uint8_t *dest;
int skip = 0, to_skip, x;
if (dst_x + width > avctx->width)
width = avctx->width - dst_x;
if (dst_y + height > avctx->height)
height = avctx->height - dst_y;
if (dst_x < 0) {
/* we need to skip the start of the scanlines */
skip = -dst_x;
if (width <= skip)
return 0;
dst_x = 0;
}
for (int y = 0; y < height; y++) {
/* one scanline at a time, size is provided */
data = next_line;
if (end - data < 2)
return 1;
line_size = bytestream_get_be16(&data);
if (end - data < line_size)
return 1;
next_line = data + line_size;
if (dst_y + y < 0)
continue;
dest = c->frame->data[0] + (dst_y + y) * c->frame->linesize[0] + dst_x;
to_skip = skip;
x = 0;
while (x < width - skip) {
int raw, size, step;
uint8_t val;
if (data >= end)
return 1;
val = bytestream_get_byte(&data);
raw = !(val & 0x80);
size = (int)(val & 0x7F) + 1;
/* skip the start of a scanline if it is off-screen */
if (to_skip >= size) {
to_skip -= size;
if (raw) {
step = size;
} else {
step = 1;
}
if (next_line - data < step)
return 1;
data += step;
continue;
} else if (to_skip) {
size -= to_skip;
if (raw) {
if (next_line - data < to_skip)
return 1;
data += to_skip;
}
to_skip = 0;
}
if (x + size >= width - skip)
size = width - skip - x;
/* either raw data, or a run of a single color */
if (raw) {
if (next_line - data < size)
return 1;
memcpy(dest + x, data, size);
data += size;
} else {
uint8_t color = bytestream_get_byte(&data);
/* ignore transparent runs */
if (color)
memset(dest + x, color, size);
}
x += size;
}
}
return 0;
}
static int cdtoons_decode_frame(AVCodecContext *avctx, void *data,
int *got_frame, AVPacket *avpkt)
{
CDToonsContext *c = avctx->priv_data;
const uint8_t *buf = avpkt->data;
const uint8_t *eod = avpkt->data + avpkt->size;
const int buf_size = avpkt->size;
uint16_t frame_id;
uint8_t background_color;
uint16_t sprite_count, sprite_offset;
uint8_t referenced_count;
uint16_t palette_id;
uint8_t palette_set;
int ret;
int saw_embedded_sprites = 0;
if (buf_size < CDTOONS_HEADER_SIZE)
return AVERROR_INVALIDDATA;
if ((ret = ff_reget_buffer(avctx, c->frame, 0)) < 0)
return ret;
/* a lot of the header is useless junk in the absence of
* dirty rectangling etc */
buf += 2; /* version? (always 9?) */
frame_id = bytestream_get_be16(&buf);
buf += 2; /* blocks_valid_until */
buf += 1;
background_color = bytestream_get_byte(&buf);
buf += 16; /* clip rect, dirty rect */
buf += 4; /* flags */
sprite_count = bytestream_get_be16(&buf);
sprite_offset = bytestream_get_be16(&buf);
buf += 2; /* max block id? */
referenced_count = bytestream_get_byte(&buf);
buf += 1;
palette_id = bytestream_get_be16(&buf);
palette_set = bytestream_get_byte(&buf);
buf += 5;
if (sprite_offset > buf_size)
return AVERROR_INVALIDDATA;
/* read new sprites introduced in this frame */
buf = avpkt->data + sprite_offset;
while (sprite_count--) {
uint32_t size;
uint16_t sprite_id;
if (buf + 14 > eod)
return AVERROR_INVALIDDATA;
sprite_id = bytestream_get_be16(&buf);
if (sprite_id >= CDTOONS_MAX_SPRITES) {
av_log(avctx, AV_LOG_ERROR,
"Sprite ID %d is too high.\n", sprite_id);
return AVERROR_INVALIDDATA;
}
if (c->sprites[sprite_id].active) {
av_log(avctx, AV_LOG_ERROR,
"Sprite ID %d is a duplicate.\n", sprite_id);
return AVERROR_INVALIDDATA;
}
c->sprites[sprite_id].flags = bytestream_get_be16(&buf);
size = bytestream_get_be32(&buf);
if (size < 14) {
av_log(avctx, AV_LOG_ERROR,
"Sprite only has %d bytes of data.\n", size);
return AVERROR_INVALIDDATA;
}
size -= 14;
c->sprites[sprite_id].size = size;
c->sprites[sprite_id].owner_frame = frame_id;
c->sprites[sprite_id].start_frame = bytestream_get_be16(&buf);
c->sprites[sprite_id].end_frame = bytestream_get_be16(&buf);
buf += 2;
if (size > buf_size || buf + size > eod)
return AVERROR_INVALIDDATA;
av_fast_padded_malloc(&c->sprites[sprite_id].data, &c->sprites[sprite_id].alloc_size, size);
if (!c->sprites[sprite_id].data)
return AVERROR(ENOMEM);
c->sprites[sprite_id].active = 1;
bytestream_get_buffer(&buf, c->sprites[sprite_id].data, size);
}
/* render any embedded sprites */
while (buf < eod) {
uint32_t tag, size;
if (buf + 8 > eod) {
av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for embedded sprites.\n");
return AVERROR_INVALIDDATA;
}
tag = bytestream_get_be32(&buf);
size = bytestream_get_be32(&buf);
if (tag == MKBETAG('D', 'i', 'f', 'f')) {
uint16_t diff_count;
if (buf + 10 > eod) {
av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame.\n");
return AVERROR_INVALIDDATA;
}
diff_count = bytestream_get_be16(&buf);
buf += 8; /* clip rect? */
for (int i = 0; i < diff_count; i++) {
int16_t top, left;
uint16_t diff_size, width, height;
if (buf + 16 > eod) {
av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame header.\n");
return AVERROR_INVALIDDATA;
}
top = bytestream_get_be16(&buf);
left = bytestream_get_be16(&buf);
buf += 4; /* bottom, right */
diff_size = bytestream_get_be32(&buf);
width = bytestream_get_be16(&buf);
height = bytestream_get_be16(&buf);
if (diff_size < 8 || diff_size - 4 > eod - buf) {
av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data for Diff frame data.\n");
return AVERROR_INVALIDDATA;
}
if (cdtoons_render_sprite(avctx, buf + 4, diff_size - 8,
left, top, width, height)) {
av_log(avctx, AV_LOG_WARNING, "Ran beyond end of sprite while rendering.\n");
}
buf += diff_size - 4;
}
saw_embedded_sprites = 1;
} else {
/* we don't care about any other entries */
if (size < 8 || size - 8 > eod - buf) {
av_log(avctx, AV_LOG_WARNING, "Ran out of data for ignored entry (size %X, %d left).\n", size, (int)(eod - buf));
return AVERROR_INVALIDDATA;
}
buf += (size - 8);
}
}
/* was an intra frame? */
if (saw_embedded_sprites)
goto done;
/* render any referenced sprites */
buf = avpkt->data + CDTOONS_HEADER_SIZE;
eod = avpkt->data + sprite_offset;
for (int i = 0; i < referenced_count; i++) {
const uint8_t *block_data;
uint16_t sprite_id, width, height;
int16_t top, left, right;
if (buf + 10 > eod) {
av_log(avctx, AV_LOG_WARNING, "Ran (seriously) out of data when rendering.\n");
return AVERROR_INVALIDDATA;
}
sprite_id = bytestream_get_be16(&buf);
top = bytestream_get_be16(&buf);
left = bytestream_get_be16(&buf);
buf += 2; /* bottom */
right = bytestream_get_be16(&buf);
if ((i == 0) && (sprite_id == 0)) {
/* clear background */
memset(c->frame->data[0], background_color,
c->frame->linesize[0] * avctx->height);
}
if (!right)
continue;
if (sprite_id >= CDTOONS_MAX_SPRITES) {
av_log(avctx, AV_LOG_ERROR,
"Sprite ID %d is too high.\n", sprite_id);
return AVERROR_INVALIDDATA;
}
block_data = c->sprites[sprite_id].data;
if (!c->sprites[sprite_id].active) {
/* this can happen when seeking around */
av_log(avctx, AV_LOG_WARNING, "Sprite %d is missing.\n", sprite_id);
continue;
}
if (c->sprites[sprite_id].size < 14) {
av_log(avctx, AV_LOG_ERROR, "Sprite %d is too small.\n", sprite_id);
continue;
}
height = bytestream_get_be16(&block_data);
width = bytestream_get_be16(&block_data);
block_data += 10;
if (cdtoons_render_sprite(avctx, block_data,
c->sprites[sprite_id].size - 14,
left, top, width, height)) {
av_log(avctx, AV_LOG_WARNING, "Ran beyond end of sprite while rendering.\n");
}
}
if (palette_id && (palette_id != c->last_pal_id)) {
if (palette_id >= CDTOONS_MAX_SPRITES) {
av_log(avctx, AV_LOG_ERROR,
"Palette ID %d is too high.\n", palette_id);
return AVERROR_INVALIDDATA;
}
if (!c->sprites[palette_id].active) {
/* this can happen when seeking around */
av_log(avctx, AV_LOG_WARNING,
"Palette ID %d is missing.\n", palette_id);
goto done;
}
if (c->sprites[palette_id].size != 256 * 2 * 3) {
av_log(avctx, AV_LOG_ERROR,
"Palette ID %d is wrong size (%d).\n",
palette_id, c->sprites[palette_id].size);
return AVERROR_INVALIDDATA;
}
c->last_pal_id = palette_id;
if (!palette_set) {
uint8_t *palette_data = c->sprites[palette_id].data;
for (int i = 0; i < 256; i++) {
/* QuickTime-ish palette: 16-bit RGB components */
unsigned r, g, b;
r = *palette_data;
g = *(palette_data + 2);
b = *(palette_data + 4);
c->pal[i] = (0xFFU << 24) | (r << 16) | (g << 8) | b;
palette_data += 6;
}
/* first palette entry indicates transparency */
c->pal[0] = 0;
c->frame->palette_has_changed = 1;
}
}
done:
/* discard outdated blocks */
for (int i = 0; i < CDTOONS_MAX_SPRITES; i++) {
if (c->sprites[i].end_frame > frame_id)
continue;
c->sprites[i].active = 0;
}
memcpy(c->frame->data[1], c->pal, AVPALETTE_SIZE);
if ((ret = av_frame_ref(data, c->frame)) < 0)
return ret;
*got_frame = 1;
/* always report that the buffer was completely consumed */
return buf_size;
}
static av_cold int cdtoons_decode_init(AVCodecContext *avctx)
{
CDToonsContext *c = avctx->priv_data;
avctx->pix_fmt = AV_PIX_FMT_PAL8;
c->last_pal_id = 0;
c->frame = av_frame_alloc();
if (!c->frame)
return AVERROR(ENOMEM);
return 0;
}
static void cdtoons_flush(AVCodecContext *avctx)
{
CDToonsContext *c = avctx->priv_data;
c->last_pal_id = 0;
for (int i = 0; i < CDTOONS_MAX_SPRITES; i++)
c->sprites[i].active = 0;
}
static av_cold int cdtoons_decode_end(AVCodecContext *avctx)
{
CDToonsContext *c = avctx->priv_data;
for (int i = 0; i < CDTOONS_MAX_SPRITES; i++) {
av_freep(&c->sprites[i].data);
c->sprites[i].active = 0;
}
av_frame_free(&c->frame);
return 0;
}
AVCodec ff_cdtoons_decoder = {
.name = "cdtoons",
.long_name = NULL_IF_CONFIG_SMALL("CDToons video"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_CDTOONS,
.priv_data_size = sizeof(CDToonsContext),
.init = cdtoons_decode_init,
.close = cdtoons_decode_end,
.decode = cdtoons_decode_frame,
.capabilities = AV_CODEC_CAP_DR1,
.flush = cdtoons_flush,
};
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