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FFmpeg/libavcodec/movtextdec.c
Michael Niedermayer 249aca8f98 avcodec/movtextdec: Check style_start/end 
Limits based on 3GPP TS 26.245 V14.0.0
Fixes: Timeout
Fixes: 6377/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOVTEXT_fuzzer-5175929115508736

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
2018-04-09 03:09:08 +02:00

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/*
* 3GPP TS 26.245 Timed Text decoder
* Copyright (c) 2012 Philip Langdale <philipl@overt.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
*/
#include "avcodec.h"
#include "ass.h"
#include "libavutil/avstring.h"
#include "libavutil/common.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#define STYLE_FLAG_BOLD (1<<0)
#define STYLE_FLAG_ITALIC (1<<1)
#define STYLE_FLAG_UNDERLINE (1<<2)
#define BOX_SIZE_INITIAL 40
#define STYL_BOX (1<<0)
#define HLIT_BOX (1<<1)
#define HCLR_BOX (1<<2)
#define TWRP_BOX (1<<3)
#define BOTTOM_LEFT 1
#define BOTTOM_CENTER 2
#define BOTTOM_RIGHT 3
#define MIDDLE_LEFT 4
#define MIDDLE_CENTER 5
#define MIDDLE_RIGHT 6
#define TOP_LEFT 7
#define TOP_CENTER 8
#define TOP_RIGHT 9
typedef struct {
char *font;
int fontsize;
int color;
int back_color;
int bold;
int italic;
int underline;
int alignment;
} MovTextDefault;
typedef struct {
uint16_t fontID;
char *font;
} FontRecord;
typedef struct {
uint16_t style_start;
uint16_t style_end;
uint8_t style_flag;
uint8_t fontsize;
uint16_t style_fontID;
} StyleBox;
typedef struct {
uint16_t hlit_start;
uint16_t hlit_end;
} HighlightBox;
typedef struct {
uint8_t hlit_color[4];
} HilightcolorBox;
typedef struct {
uint8_t wrap_flag;
} TextWrapBox;
typedef struct {
StyleBox **s;
StyleBox *s_temp;
HighlightBox h;
HilightcolorBox c;
FontRecord **ftab;
FontRecord *ftab_temp;
TextWrapBox w;
MovTextDefault d;
uint8_t box_flags;
uint16_t style_entries, ftab_entries;
uint64_t tracksize;
int size_var;
int count_s, count_f;
int readorder;
} MovTextContext;
typedef struct {
uint32_t type;
size_t base_size;
int (*decode)(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt);
} Box;
static void mov_text_cleanup(MovTextContext *m)
{
int i;
if (m->box_flags & STYL_BOX) {
for(i = 0; i < m->count_s; i++) {
av_freep(&m->s[i]);
}
av_freep(&m->s);
m->count_s = 0;
m->style_entries = 0;
}
}
static void mov_text_cleanup_ftab(MovTextContext *m)
{
int i;
if (m->ftab_temp)
av_freep(&m->ftab_temp->font);
av_freep(&m->ftab_temp);
if (m->ftab) {
for(i = 0; i < m->count_f; i++) {
av_freep(&m->ftab[i]->font);
av_freep(&m->ftab[i]);
}
}
av_freep(&m->ftab);
}
static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
{
uint8_t *tx3g_ptr = avctx->extradata;
int i, box_size, font_length;
int8_t v_align, h_align;
int style_fontID;
StyleBox s_default;
m->count_f = 0;
m->ftab_entries = 0;
box_size = BOX_SIZE_INITIAL; /* Size till ftab_entries */
if (avctx->extradata_size < box_size)
return -1;
// Display Flags
tx3g_ptr += 4;
// Alignment
h_align = *tx3g_ptr++;
v_align = *tx3g_ptr++;
if (h_align == 0) {
if (v_align == 0)
m->d.alignment = TOP_LEFT;
if (v_align == 1)
m->d.alignment = MIDDLE_LEFT;
if (v_align == -1)
m->d.alignment = BOTTOM_LEFT;
}
if (h_align == 1) {
if (v_align == 0)
m->d.alignment = TOP_CENTER;
if (v_align == 1)
m->d.alignment = MIDDLE_CENTER;
if (v_align == -1)
m->d.alignment = BOTTOM_CENTER;
}
if (h_align == -1) {
if (v_align == 0)
m->d.alignment = TOP_RIGHT;
if (v_align == 1)
m->d.alignment = MIDDLE_RIGHT;
if (v_align == -1)
m->d.alignment = BOTTOM_RIGHT;
}
// Background Color
m->d.back_color = AV_RB24(tx3g_ptr);
tx3g_ptr += 4;
// BoxRecord
tx3g_ptr += 8;
// StyleRecord
tx3g_ptr += 4;
// fontID
style_fontID = AV_RB16(tx3g_ptr);
tx3g_ptr += 2;
// face-style-flags
s_default.style_flag = *tx3g_ptr++;
m->d.bold = s_default.style_flag & STYLE_FLAG_BOLD;
m->d.italic = s_default.style_flag & STYLE_FLAG_ITALIC;
m->d.underline = s_default.style_flag & STYLE_FLAG_UNDERLINE;
// fontsize
m->d.fontsize = *tx3g_ptr++;
// Primary color
m->d.color = AV_RB24(tx3g_ptr);
tx3g_ptr += 4;
// FontRecord
// FontRecord Size
tx3g_ptr += 4;
// ftab
tx3g_ptr += 4;
m->ftab_entries = AV_RB16(tx3g_ptr);
tx3g_ptr += 2;
for (i = 0; i < m->ftab_entries; i++) {
box_size += 3;
if (avctx->extradata_size < box_size) {
mov_text_cleanup_ftab(m);
m->ftab_entries = 0;
return -1;
}
m->ftab_temp = av_mallocz(sizeof(*m->ftab_temp));
if (!m->ftab_temp) {
mov_text_cleanup_ftab(m);
return AVERROR(ENOMEM);
}
m->ftab_temp->fontID = AV_RB16(tx3g_ptr);
tx3g_ptr += 2;
font_length = *tx3g_ptr++;
box_size = box_size + font_length;
if (avctx->extradata_size < box_size) {
mov_text_cleanup_ftab(m);
m->ftab_entries = 0;
return -1;
}
m->ftab_temp->font = av_malloc(font_length + 1);
if (!m->ftab_temp->font) {
mov_text_cleanup_ftab(m);
return AVERROR(ENOMEM);
}
memcpy(m->ftab_temp->font, tx3g_ptr, font_length);
m->ftab_temp->font[font_length] = '\0';
av_dynarray_add(&m->ftab, &m->count_f, m->ftab_temp);
if (!m->ftab) {
mov_text_cleanup_ftab(m);
return AVERROR(ENOMEM);
}
m->ftab_temp = NULL;
tx3g_ptr = tx3g_ptr + font_length;
}
for (i = 0; i < m->ftab_entries; i++) {
if (style_fontID == m->ftab[i]->fontID)
m->d.font = m->ftab[i]->font;
}
return 0;
}
static int decode_twrp(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
m->box_flags |= TWRP_BOX;
m->w.wrap_flag = *tsmb++;
return 0;
}
static int decode_hlit(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
m->box_flags |= HLIT_BOX;
m->h.hlit_start = AV_RB16(tsmb);
tsmb += 2;
m->h.hlit_end = AV_RB16(tsmb);
tsmb += 2;
return 0;
}
static int decode_hclr(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
m->box_flags |= HCLR_BOX;
memcpy(m->c.hlit_color, tsmb, 4);
tsmb += 4;
return 0;
}
static int decode_styl(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
int i;
int style_entries = AV_RB16(tsmb);
tsmb += 2;
// A single style record is of length 12 bytes.
if (m->tracksize + m->size_var + 2 + style_entries * 12 > avpkt->size)
return -1;
m->style_entries = style_entries;
m->box_flags |= STYL_BOX;
for(i = 0; i < m->style_entries; i++) {
m->s_temp = av_malloc(sizeof(*m->s_temp));
if (!m->s_temp) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
m->s_temp->style_start = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_end = AV_RB16(tsmb);
if ( m->s_temp->style_end < m->s_temp->style_start
|| (m->count_s && m->s_temp->style_start < m->s[m->count_s - 1]->style_end)) {
av_freep(&m->s_temp);
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
tsmb += 2;
m->s_temp->style_fontID = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_flag = AV_RB8(tsmb);
tsmb++;
m->s_temp->fontsize = AV_RB8(tsmb);
av_dynarray_add(&m->s, &m->count_s, m->s_temp);
if(!m->s) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
tsmb++;
// text-color-rgba
tsmb += 4;
}
return 0;
}
static const Box box_types[] = {
{ MKBETAG('s','t','y','l'), 2, decode_styl },
{ MKBETAG('h','l','i','t'), 4, decode_hlit },
{ MKBETAG('h','c','l','r'), 4, decode_hclr },
{ MKBETAG('t','w','r','p'), 1, decode_twrp }
};
const static size_t box_count = FF_ARRAY_ELEMS(box_types);
// Return byte length of the UTF-8 sequence starting at text[0]. 0 on error.
static int get_utf8_length_at(const char *text, const char *text_end)
{
const char *start = text;
int err = 0;
uint32_t c;
GET_UTF8(c, text < text_end ? (uint8_t)*text++ : (err = 1, 0), goto error;);
if (err)
goto error;
return text - start;
error:
return 0;
}
static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
int i = 0;
int j = 0;
int text_pos = 0;
if (text < text_end && m->box_flags & TWRP_BOX) {
if (m->w.wrap_flag == 1) {
av_bprintf(buf, "{\\q1}"); /* End of line wrap */
} else {
av_bprintf(buf, "{\\q2}"); /* No wrap */
}
}
while (text < text_end) {
int len;
if (m->box_flags & STYL_BOX) {
for (i = 0; i < m->style_entries; i++) {
if (m->s[i]->style_flag && text_pos == m->s[i]->style_end) {
av_bprintf(buf, "{\\r}");
}
}
for (i = 0; i < m->style_entries; i++) {
if (m->s[i]->style_flag && text_pos == m->s[i]->style_start) {
if (m->s[i]->style_flag & STYLE_FLAG_BOLD)
av_bprintf(buf, "{\\b1}");
if (m->s[i]->style_flag & STYLE_FLAG_ITALIC)
av_bprintf(buf, "{\\i1}");
if (m->s[i]->style_flag & STYLE_FLAG_UNDERLINE)
av_bprintf(buf, "{\\u1}");
av_bprintf(buf, "{\\fs%d}", m->s[i]->fontsize);
for (j = 0; j < m->ftab_entries; j++) {
if (m->s[i]->style_fontID == m->ftab[j]->fontID)
av_bprintf(buf, "{\\fn%s}", m->ftab[j]->font);
}
}
}
}
if (m->box_flags & HLIT_BOX) {
if (text_pos == m->h.hlit_start) {
/* If hclr box is present, set the secondary color to the color
* specified. Otherwise, set primary color to white and secondary
* color to black. These colors will come from TextSampleModifier
* boxes in future and inverse video technique for highlight will
* be implemented.
*/
if (m->box_flags & HCLR_BOX) {
av_bprintf(buf, "{\\2c&H%02x%02x%02x&}", m->c.hlit_color[2],
m->c.hlit_color[1], m->c.hlit_color[0]);
} else {
av_bprintf(buf, "{\\1c&H000000&}{\\2c&HFFFFFF&}");
}
}
if (text_pos == m->h.hlit_end) {
if (m->box_flags & HCLR_BOX) {
av_bprintf(buf, "{\\2c&H000000&}");
} else {
av_bprintf(buf, "{\\1c&HFFFFFF&}{\\2c&H000000&}");
}
}
}
len = get_utf8_length_at(text, text_end);
if (len < 1) {
av_log(avctx, AV_LOG_ERROR, "invalid UTF-8 byte in subtitle\n");
len = 1;
}
for (i = 0; i < len; i++) {
switch (*text) {
case '\r':
break;
case '\n':
av_bprintf(buf, "\\N");
break;
default:
av_bprint_chars(buf, *text, 1);
break;
}
text++;
}
text_pos++;
}
return 0;
}
static int mov_text_init(AVCodecContext *avctx) {
/*
* TODO: Handle the default text style.
* NB: Most players ignore styles completely, with the result that
* it's very common to find files where the default style is broken
* and respecting it results in a worse experience than ignoring it.
*/
int ret;
MovTextContext *m = avctx->priv_data;
ret = mov_text_tx3g(avctx, m);
if (ret == 0) {
return ff_ass_subtitle_header(avctx, m->d.font, m->d.fontsize, m->d.color,
m->d.back_color, m->d.bold, m->d.italic,
m->d.underline, ASS_DEFAULT_BORDERSTYLE,
m->d.alignment);
} else
return ff_ass_subtitle_header_default(avctx);
}
static int mov_text_decode_frame(AVCodecContext *avctx,
void *data, int *got_sub_ptr, AVPacket *avpkt)
{
AVSubtitle *sub = data;
MovTextContext *m = avctx->priv_data;
int ret;
AVBPrint buf;
char *ptr = avpkt->data;
char *end;
int text_length, tsmb_type, ret_tsmb;
uint64_t tsmb_size;
const uint8_t *tsmb;
size_t i;
if (!ptr || avpkt->size < 2)
return AVERROR_INVALIDDATA;
/*
* A packet of size two with value zero is an empty subtitle
* used to mark the end of the previous non-empty subtitle.
* We can just drop them here as we have duration information
* already. If the value is non-zero, then it's technically a
* bad packet.
*/
if (avpkt->size == 2)
return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
/*
* The first two bytes of the packet are the length of the text string
* In complex cases, there are style descriptors appended to the string
* so we can't just assume the packet size is the string size.
*/
text_length = AV_RB16(ptr);
end = ptr + FFMIN(2 + text_length, avpkt->size);
ptr += 2;
mov_text_cleanup(m);
tsmb_size = 0;
m->tracksize = 2 + text_length;
m->style_entries = 0;
m->box_flags = 0;
m->count_s = 0;
// Note that the spec recommends lines be no longer than 2048 characters.
av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
if (text_length + 2 != avpkt->size) {
while (m->tracksize + 8 <= avpkt->size) {
// A box is a minimum of 8 bytes.
tsmb = ptr + m->tracksize - 2;
tsmb_size = AV_RB32(tsmb);
tsmb += 4;
tsmb_type = AV_RB32(tsmb);
tsmb += 4;
if (tsmb_size == 1) {
if (m->tracksize + 16 > avpkt->size)
break;
tsmb_size = AV_RB64(tsmb);
tsmb += 8;
m->size_var = 16;
} else
m->size_var = 8;
//size_var is equal to 8 or 16 depending on the size of box
if (tsmb_size == 0) {
av_log(avctx, AV_LOG_ERROR, "tsmb_size is 0\n");
return AVERROR_INVALIDDATA;
}
if (tsmb_size > avpkt->size - m->tracksize)
break;
for (i = 0; i < box_count; i++) {
if (tsmb_type == box_types[i].type) {
if (m->tracksize + m->size_var + box_types[i].base_size > avpkt->size)
break;
ret_tsmb = box_types[i].decode(tsmb, m, avpkt);
if (ret_tsmb == -1)
break;
}
}
m->tracksize = m->tracksize + tsmb_size;
}
text_to_ass(&buf, ptr, end, avctx);
mov_text_cleanup(m);
} else
text_to_ass(&buf, ptr, end, avctx);
ret = ff_ass_add_rect(sub, buf.str, m->readorder++, 0, NULL, NULL);
av_bprint_finalize(&buf, NULL);
if (ret < 0)
return ret;
*got_sub_ptr = sub->num_rects > 0;
return avpkt->size;
}
static int mov_text_decode_close(AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
mov_text_cleanup_ftab(m);
mov_text_cleanup(m);
return 0;
}
static void mov_text_flush(AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
m->readorder = 0;
}
AVCodec ff_movtext_decoder = {
.name = "mov_text",
.long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_MOV_TEXT,
.priv_data_size = sizeof(MovTextContext),
.init = mov_text_init,
.decode = mov_text_decode_frame,
.close = mov_text_decode_close,
.flush = mov_text_flush,
};
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