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FFmpeg/libavcodec/cbs.c
Andreas Rheinhardt ac5d5046c8 avcodec/cbs: Fix potential double-free when adding unit fails 
ff_cbs_insert_unit_data() has two modes of operation: It can insert a
unit with a newly created reference to an already existing AVBuffer; or
it can take a buffer and create an AVBuffer for it. Said buffer will
then become owned by the unit lateron.

A potential memleak/double-free exists in the second case, because if
creating the AVBuffer fails, the function immediately returns, but when
it fails lateron, the supplied buffer will be freed. The caller has no
way to distinguish between these two outcomes. The only such caller
(cbs_jpeg_split_fragment() in cbs_jpeg.c) opted for a potential
double-free.

This commit changes this by explicitly stating that a non-refcounted
buffer will be freed on error. The aforementioned caller has been
brought in line with this.

Fixes CID 1452623.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-02-09 22:23:29 +00:00

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/*
* 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 "config.h"
#include "libavutil/avassert.h"
#include "libavutil/buffer.h"
#include "libavutil/common.h"
#include "cbs.h"
#include "cbs_internal.h"
static const CodedBitstreamType *cbs_type_table[] = {
#if CONFIG_CBS_AV1
&ff_cbs_type_av1,
#endif
#if CONFIG_CBS_H264
&ff_cbs_type_h264,
#endif
#if CONFIG_CBS_H265
&ff_cbs_type_h265,
#endif
#if CONFIG_CBS_JPEG
&ff_cbs_type_jpeg,
#endif
#if CONFIG_CBS_MPEG2
&ff_cbs_type_mpeg2,
#endif
#if CONFIG_CBS_VP9
&ff_cbs_type_vp9,
#endif
};
const enum AVCodecID ff_cbs_all_codec_ids[] = {
#if CONFIG_CBS_AV1
AV_CODEC_ID_AV1,
#endif
#if CONFIG_CBS_H264
AV_CODEC_ID_H264,
#endif
#if CONFIG_CBS_H265
AV_CODEC_ID_H265,
#endif
#if CONFIG_CBS_JPEG
AV_CODEC_ID_MJPEG,
#endif
#if CONFIG_CBS_MPEG2
AV_CODEC_ID_MPEG2VIDEO,
#endif
#if CONFIG_CBS_VP9
AV_CODEC_ID_VP9,
#endif
AV_CODEC_ID_NONE
};
int ff_cbs_init(CodedBitstreamContext **ctx_ptr,
enum AVCodecID codec_id, void *log_ctx)
{
CodedBitstreamContext *ctx;
const CodedBitstreamType *type;
int i;
type = NULL;
for (i = 0; i < FF_ARRAY_ELEMS(cbs_type_table); i++) {
if (cbs_type_table[i]->codec_id == codec_id) {
type = cbs_type_table[i];
break;
}
}
if (!type)
return AVERROR(EINVAL);
ctx = av_mallocz(sizeof(*ctx));
if (!ctx)
return AVERROR(ENOMEM);
ctx->log_ctx = log_ctx;
ctx->codec = type;
if (type->priv_data_size) {
ctx->priv_data = av_mallocz(ctx->codec->priv_data_size);
if (!ctx->priv_data) {
av_freep(&ctx);
return AVERROR(ENOMEM);
}
}
ctx->decompose_unit_types = NULL;
ctx->trace_enable = 0;
ctx->trace_level = AV_LOG_TRACE;
*ctx_ptr = ctx;
return 0;
}
void ff_cbs_close(CodedBitstreamContext **ctx_ptr)
{
CodedBitstreamContext *ctx = *ctx_ptr;
if (!ctx)
return;
if (ctx->codec && ctx->codec->close)
ctx->codec->close(ctx);
av_freep(&ctx->write_buffer);
av_freep(&ctx->priv_data);
av_freep(ctx_ptr);
}
static void cbs_unit_uninit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
av_buffer_unref(&unit->content_ref);
unit->content = NULL;
av_buffer_unref(&unit->data_ref);
unit->data = NULL;
unit->data_size = 0;
unit->data_bit_padding = 0;
}
void ff_cbs_fragment_reset(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
int i;
for (i = 0; i < frag->nb_units; i++)
cbs_unit_uninit(ctx, &frag->units[i]);
frag->nb_units = 0;
av_buffer_unref(&frag->data_ref);
frag->data = NULL;
frag->data_size = 0;
frag->data_bit_padding = 0;
}
void ff_cbs_fragment_free(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
ff_cbs_fragment_reset(ctx, frag);
av_freep(&frag->units);
frag->nb_units_allocated = 0;
}
static int cbs_read_fragment_content(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
int err, i, j;
for (i = 0; i < frag->nb_units; i++) {
CodedBitstreamUnit *unit = &frag->units[i];
if (ctx->decompose_unit_types) {
for (j = 0; j < ctx->nb_decompose_unit_types; j++) {
if (ctx->decompose_unit_types[j] == unit->type)
break;
}
if (j >= ctx->nb_decompose_unit_types)
continue;
}
av_buffer_unref(&unit->content_ref);
unit->content = NULL;
av_assert0(unit->data && unit->data_ref);
err = ctx->codec->read_unit(ctx, unit);
if (err == AVERROR(ENOSYS)) {
av_log(ctx->log_ctx, AV_LOG_VERBOSE,
"Decomposition unimplemented for unit %d "
"(type %"PRIu32").\n", i, unit->type);
} else if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Failed to read unit %d "
"(type %"PRIu32").\n", i, unit->type);
return err;
}
}
return 0;
}
static int cbs_fill_fragment_data(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
const uint8_t *data, size_t size)
{
av_assert0(!frag->data && !frag->data_ref);
frag->data_ref =
av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!frag->data_ref)
return AVERROR(ENOMEM);
frag->data = frag->data_ref->data;
frag->data_size = size;
memcpy(frag->data, data, size);
memset(frag->data + size, 0,
AV_INPUT_BUFFER_PADDING_SIZE);
return 0;
}
int ff_cbs_read_extradata(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
const AVCodecParameters *par)
{
int err;
err = cbs_fill_fragment_data(ctx, frag, par->extradata,
par->extradata_size);
if (err < 0)
return err;
err = ctx->codec->split_fragment(ctx, frag, 1);
if (err < 0)
return err;
return cbs_read_fragment_content(ctx, frag);
}
int ff_cbs_read_packet(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
const AVPacket *pkt)
{
int err;
if (pkt->buf) {
frag->data_ref = av_buffer_ref(pkt->buf);
if (!frag->data_ref)
return AVERROR(ENOMEM);
frag->data = pkt->data;
frag->data_size = pkt->size;
} else {
err = cbs_fill_fragment_data(ctx, frag, pkt->data, pkt->size);
if (err < 0)
return err;
}
err = ctx->codec->split_fragment(ctx, frag, 0);
if (err < 0)
return err;
return cbs_read_fragment_content(ctx, frag);
}
int ff_cbs_read(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
const uint8_t *data, size_t size)
{
int err;
err = cbs_fill_fragment_data(ctx, frag, data, size);
if (err < 0)
return err;
err = ctx->codec->split_fragment(ctx, frag, 0);
if (err < 0)
return err;
return cbs_read_fragment_content(ctx, frag);
}
static int cbs_write_unit_data(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
PutBitContext pbc;
int ret;
if (!ctx->write_buffer) {
// Initial write buffer size is 1MB.
ctx->write_buffer_size = 1024 * 1024;
reallocate_and_try_again:
ret = av_reallocp(&ctx->write_buffer, ctx->write_buffer_size);
if (ret < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
"sufficiently large write buffer (last attempt "
"%"SIZE_SPECIFIER" bytes).\n", ctx->write_buffer_size);
return ret;
}
}
init_put_bits(&pbc, ctx->write_buffer, ctx->write_buffer_size);
ret = ctx->codec->write_unit(ctx, unit, &pbc);
if (ret < 0) {
if (ret == AVERROR(ENOSPC)) {
// Overflow.
if (ctx->write_buffer_size == INT_MAX / 8)
return AVERROR(ENOMEM);
ctx->write_buffer_size = FFMIN(2 * ctx->write_buffer_size, INT_MAX / 8);
goto reallocate_and_try_again;
}
// Write failed for some other reason.
return ret;
}
// Overflow but we didn't notice.
av_assert0(put_bits_count(&pbc) <= 8 * ctx->write_buffer_size);
if (put_bits_count(&pbc) % 8)
unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
else
unit->data_bit_padding = 0;
flush_put_bits(&pbc);
ret = ff_cbs_alloc_unit_data(ctx, unit, put_bits_count(&pbc) / 8);
if (ret < 0)
return ret;
memcpy(unit->data, ctx->write_buffer, unit->data_size);
return 0;
}
int ff_cbs_write_fragment_data(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
int err, i;
for (i = 0; i < frag->nb_units; i++) {
CodedBitstreamUnit *unit = &frag->units[i];
if (!unit->content)
continue;
av_buffer_unref(&unit->data_ref);
unit->data = NULL;
err = cbs_write_unit_data(ctx, unit);
if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Failed to write unit %d "
"(type %"PRIu32").\n", i, unit->type);
return err;
}
av_assert0(unit->data && unit->data_ref);
}
av_buffer_unref(&frag->data_ref);
frag->data = NULL;
err = ctx->codec->assemble_fragment(ctx, frag);
if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Failed to assemble fragment.\n");
return err;
}
av_assert0(frag->data && frag->data_ref);
return 0;
}
int ff_cbs_write_extradata(CodedBitstreamContext *ctx,
AVCodecParameters *par,
CodedBitstreamFragment *frag)
{
int err;
err = ff_cbs_write_fragment_data(ctx, frag);
if (err < 0)
return err;
av_freep(&par->extradata);
par->extradata = av_malloc(frag->data_size +
AV_INPUT_BUFFER_PADDING_SIZE);
if (!par->extradata)
return AVERROR(ENOMEM);
memcpy(par->extradata, frag->data, frag->data_size);
memset(par->extradata + frag->data_size, 0,
AV_INPUT_BUFFER_PADDING_SIZE);
par->extradata_size = frag->data_size;
return 0;
}
int ff_cbs_write_packet(CodedBitstreamContext *ctx,
AVPacket *pkt,
CodedBitstreamFragment *frag)
{
AVBufferRef *buf;
int err;
err = ff_cbs_write_fragment_data(ctx, frag);
if (err < 0)
return err;
buf = av_buffer_ref(frag->data_ref);
if (!buf)
return AVERROR(ENOMEM);
av_buffer_unref(&pkt->buf);
pkt->buf = buf;
pkt->data = frag->data;
pkt->size = frag->data_size;
return 0;
}
void ff_cbs_trace_header(CodedBitstreamContext *ctx,
const char *name)
{
if (!ctx->trace_enable)
return;
av_log(ctx->log_ctx, ctx->trace_level, "%s\n", name);
}
void ff_cbs_trace_syntax_element(CodedBitstreamContext *ctx, int position,
const char *str, const int *subscripts,
const char *bits, int64_t value)
{
char name[256];
size_t name_len, bits_len;
int pad, subs, i, j, k, n;
if (!ctx->trace_enable)
return;
av_assert0(value >= INT_MIN && value <= UINT32_MAX);
subs = subscripts ? subscripts[0] : 0;
n = 0;
for (i = j = 0; str[i];) {
if (str[i] == '[') {
if (n < subs) {
++n;
k = snprintf(name + j, sizeof(name) - j, "[%d", subscripts[n]);
av_assert0(k > 0 && j + k < sizeof(name));
j += k;
for (++i; str[i] && str[i] != ']'; i++);
av_assert0(str[i] == ']');
} else {
while (str[i] && str[i] != ']')
name[j++] = str[i++];
av_assert0(str[i] == ']');
}
} else {
av_assert0(j + 1 < sizeof(name));
name[j++] = str[i++];
}
}
av_assert0(j + 1 < sizeof(name));
name[j] = 0;
av_assert0(n == subs);
name_len = strlen(name);
bits_len = strlen(bits);
if (name_len + bits_len > 60)
pad = bits_len + 2;
else
pad = 61 - name_len;
av_log(ctx->log_ctx, ctx->trace_level, "%-10d %s%*s = %"PRId64"\n",
position, name, pad, bits, value);
}
int ff_cbs_read_unsigned(CodedBitstreamContext *ctx, GetBitContext *gbc,
int width, const char *name,
const int *subscripts, uint32_t *write_to,
uint32_t range_min, uint32_t range_max)
{
uint32_t value;
int position;
av_assert0(width > 0 && width <= 32);
if (get_bits_left(gbc) < width) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid value at "
"%s: bitstream ended.\n", name);
return AVERROR_INVALIDDATA;
}
if (ctx->trace_enable)
position = get_bits_count(gbc);
value = get_bits_long(gbc, width);
if (ctx->trace_enable) {
char bits[33];
int i;
for (i = 0; i < width; i++)
bits[i] = value >> (width - i - 1) & 1 ? '1' : '0';
bits[i] = 0;
ff_cbs_trace_syntax_element(ctx, position, name, subscripts,
bits, value);
}
if (value < range_min || value > range_max) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: "
"%"PRIu32", but must be in [%"PRIu32",%"PRIu32"].\n",
name, value, range_min, range_max);
return AVERROR_INVALIDDATA;
}
*write_to = value;
return 0;
}
int ff_cbs_write_unsigned(CodedBitstreamContext *ctx, PutBitContext *pbc,
int width, const char *name,
const int *subscripts, uint32_t value,
uint32_t range_min, uint32_t range_max)
{
av_assert0(width > 0 && width <= 32);
if (value < range_min || value > range_max) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: "
"%"PRIu32", but must be in [%"PRIu32",%"PRIu32"].\n",
name, value, range_min, range_max);
return AVERROR_INVALIDDATA;
}
if (put_bits_left(pbc) < width)
return AVERROR(ENOSPC);
if (ctx->trace_enable) {
char bits[33];
int i;
for (i = 0; i < width; i++)
bits[i] = value >> (width - i - 1) & 1 ? '1' : '0';
bits[i] = 0;
ff_cbs_trace_syntax_element(ctx, put_bits_count(pbc),
name, subscripts, bits, value);
}
if (width < 32)
put_bits(pbc, width, value);
else
put_bits32(pbc, value);
return 0;
}
int ff_cbs_read_signed(CodedBitstreamContext *ctx, GetBitContext *gbc,
int width, const char *name,
const int *subscripts, int32_t *write_to,
int32_t range_min, int32_t range_max)
{
int32_t value;
int position;
av_assert0(width > 0 && width <= 32);
if (get_bits_left(gbc) < width) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid value at "
"%s: bitstream ended.\n", name);
return AVERROR_INVALIDDATA;
}
if (ctx->trace_enable)
position = get_bits_count(gbc);
value = get_sbits_long(gbc, width);
if (ctx->trace_enable) {
char bits[33];
int i;
for (i = 0; i < width; i++)
bits[i] = value & (1U << (width - i - 1)) ? '1' : '0';
bits[i] = 0;
ff_cbs_trace_syntax_element(ctx, position, name, subscripts,
bits, value);
}
if (value < range_min || value > range_max) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: "
"%"PRId32", but must be in [%"PRId32",%"PRId32"].\n",
name, value, range_min, range_max);
return AVERROR_INVALIDDATA;
}
*write_to = value;
return 0;
}
int ff_cbs_write_signed(CodedBitstreamContext *ctx, PutBitContext *pbc,
int width, const char *name,
const int *subscripts, int32_t value,
int32_t range_min, int32_t range_max)
{
av_assert0(width > 0 && width <= 32);
if (value < range_min || value > range_max) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "%s out of range: "
"%"PRId32", but must be in [%"PRId32",%"PRId32"].\n",
name, value, range_min, range_max);
return AVERROR_INVALIDDATA;
}
if (put_bits_left(pbc) < width)
return AVERROR(ENOSPC);
if (ctx->trace_enable) {
char bits[33];
int i;
for (i = 0; i < width; i++)
bits[i] = value & (1U << (width - i - 1)) ? '1' : '0';
bits[i] = 0;
ff_cbs_trace_syntax_element(ctx, put_bits_count(pbc),
name, subscripts, bits, value);
}
if (width < 32)
put_sbits(pbc, width, value);
else
put_bits32(pbc, value);
return 0;
}
int ff_cbs_alloc_unit_content(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
size_t size,
void (*free)(void *opaque, uint8_t *data))
{
av_assert0(!unit->content && !unit->content_ref);
unit->content = av_mallocz(size);
if (!unit->content)
return AVERROR(ENOMEM);
unit->content_ref = av_buffer_create(unit->content, size,
free, NULL, 0);
if (!unit->content_ref) {
av_freep(&unit->content);
return AVERROR(ENOMEM);
}
return 0;
}
int ff_cbs_alloc_unit_data(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
size_t size)
{
av_assert0(!unit->data && !unit->data_ref);
unit->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!unit->data_ref)
return AVERROR(ENOMEM);
unit->data = unit->data_ref->data;
unit->data_size = size;
memset(unit->data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
return 0;
}
static int cbs_insert_unit(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int position)
{
CodedBitstreamUnit *units;
if (frag->nb_units < frag->nb_units_allocated) {
units = frag->units;
if (position < frag->nb_units)
memmove(units + position + 1, units + position,
(frag->nb_units - position) * sizeof(*units));
} else {
units = av_malloc_array(frag->nb_units + 1, sizeof(*units));
if (!units)
return AVERROR(ENOMEM);
++frag->nb_units_allocated;
if (position > 0)
memcpy(units, frag->units, position * sizeof(*units));
if (position < frag->nb_units)
memcpy(units + position + 1, frag->units + position,
(frag->nb_units - position) * sizeof(*units));
}
memset(units + position, 0, sizeof(*units));
if (units != frag->units) {
av_free(frag->units);
frag->units = units;
}
++frag->nb_units;
return 0;
}
int ff_cbs_insert_unit_content(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int position,
CodedBitstreamUnitType type,
void *content,
AVBufferRef *content_buf)
{
CodedBitstreamUnit *unit;
AVBufferRef *content_ref;
int err;
if (position == -1)
position = frag->nb_units;
av_assert0(position >= 0 && position <= frag->nb_units);
if (content_buf) {
content_ref = av_buffer_ref(content_buf);
if (!content_ref)
return AVERROR(ENOMEM);
} else {
content_ref = NULL;
}
err = cbs_insert_unit(ctx, frag, position);
if (err < 0) {
av_buffer_unref(&content_ref);
return err;
}
unit = &frag->units[position];
unit->type = type;
unit->content = content;
unit->content_ref = content_ref;
return 0;
}
int ff_cbs_insert_unit_data(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int position,
CodedBitstreamUnitType type,
uint8_t *data, size_t data_size,
AVBufferRef *data_buf)
{
CodedBitstreamUnit *unit;
AVBufferRef *data_ref;
int err;
if (position == -1)
position = frag->nb_units;
av_assert0(position >= 0 && position <= frag->nb_units);
if (data_buf)
data_ref = av_buffer_ref(data_buf);
else
data_ref = av_buffer_create(data, data_size, NULL, NULL, 0);
if (!data_ref) {
if (!data_buf)
av_free(data);
return AVERROR(ENOMEM);
}
err = cbs_insert_unit(ctx, frag, position);
if (err < 0) {
av_buffer_unref(&data_ref);
return err;
}
unit = &frag->units[position];
unit->type = type;
unit->data = data;
unit->data_size = data_size;
unit->data_ref = data_ref;
return 0;
}
void ff_cbs_delete_unit(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int position)
{
av_assert0(0 <= position && position < frag->nb_units
&& "Unit to be deleted not in fragment.");
cbs_unit_uninit(ctx, &frag->units[position]);
--frag->nb_units;
if (frag->nb_units > 0)
memmove(frag->units + position,
frag->units + position + 1,
(frag->nb_units - position) * sizeof(*frag->units));
}
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