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FFmpeg/libavcodec/h2645_parse.c
Andreas Rheinhardt a217c1472d avcodec/h2645_parse: Only trim RBSP trailing padding if it exists 
It does not exist for NALUs for which the SODB is empty;
it also does not exist for NALUs for which not even
the complete header is present. The former category contains
end of sequence and end of bitstream units. The latter category
consists of one-byte HEVC units (the ordinary H.264 header is only
one byte long).
This commit therefore stops stripping RBSP trailing padding
from the former type of unit and discards the latter type of unit
altogether.

This also fixes an assertion failure: Before this commit, a one-byte
HEVC NALU from an ISOBMFF packet could pass all the checks in
hevc_parse_nal_header() (because the first byte of the size field
of the next unit is mistaken as containing the temporal_id);
yet because the trailing padding bits were stripped, its actually
had a size of less than eight bits; because h2645_parse.c uses
the checked bitstream reader, the get_bits_count() of the GetBitContext
is not 16 in this case; it is not even a multiple of eight
and this can trigger an assert in ff_hevc_decode_nal_sei().

Fixes: Assertion failure
Fixes: 46662/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HEVC_fuzzer-4947860854013952

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-06-24 18:31:03 +02:00

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/*
* H.264/HEVC common parsing code
*
* 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/intmath.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "bytestream.h"
#include "hevc.h"
#include "h264.h"
#include "h2645_parse.h"
int ff_h2645_extract_rbsp(const uint8_t *src, int length,
H2645RBSP *rbsp, H2645NAL *nal, int small_padding)
{
int i, si, di;
uint8_t *dst;
nal->skipped_bytes = 0;
#define STARTCODE_TEST \
if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) { \
if (src[i + 2] != 3 && src[i + 2] != 0) { \
/* startcode, so we must be past the end */ \
length = i; \
} \
break; \
}
#if HAVE_FAST_UNALIGNED
#define FIND_FIRST_ZERO \
if (i > 0 && !src[i]) \
i--; \
while (src[i]) \
i++
#if HAVE_FAST_64BIT
for (i = 0; i + 1 < length; i += 9) {
if (!((~AV_RN64(src + i) &
(AV_RN64(src + i) - 0x0100010001000101ULL)) &
0x8000800080008080ULL))
continue;
FIND_FIRST_ZERO;
STARTCODE_TEST;
i -= 7;
}
#else
for (i = 0; i + 1 < length; i += 5) {
if (!((~AV_RN32(src + i) &
(AV_RN32(src + i) - 0x01000101U)) &
0x80008080U))
continue;
FIND_FIRST_ZERO;
STARTCODE_TEST;
i -= 3;
}
#endif /* HAVE_FAST_64BIT */
#else
for (i = 0; i + 1 < length; i += 2) {
if (src[i])
continue;
if (i > 0 && src[i - 1] == 0)
i--;
STARTCODE_TEST;
}
#endif /* HAVE_FAST_UNALIGNED */
if (i >= length - 1 && small_padding) { // no escaped 0
nal->data =
nal->raw_data = src;
nal->size =
nal->raw_size = length;
return length;
} else if (i > length)
i = length;
dst = &rbsp->rbsp_buffer[rbsp->rbsp_buffer_size];
memcpy(dst, src, i);
si = di = i;
while (si + 2 < length) {
// remove escapes (very rare 1:2^22)
if (src[si + 2] > 3) {
dst[di++] = src[si++];
dst[di++] = src[si++];
} else if (src[si] == 0 && src[si + 1] == 0 && src[si + 2] != 0) {
if (src[si + 2] == 3) { // escape
dst[di++] = 0;
dst[di++] = 0;
si += 3;
if (nal->skipped_bytes_pos) {
nal->skipped_bytes++;
if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
nal->skipped_bytes_pos_size *= 2;
av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
av_reallocp_array(&nal->skipped_bytes_pos,
nal->skipped_bytes_pos_size,
sizeof(*nal->skipped_bytes_pos));
if (!nal->skipped_bytes_pos) {
nal->skipped_bytes_pos_size = 0;
return AVERROR(ENOMEM);
}
}
if (nal->skipped_bytes_pos)
nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
}
continue;
} else // next start code
goto nsc;
}
dst[di++] = src[si++];
}
while (si < length)
dst[di++] = src[si++];
nsc:
memset(dst + di, 0, AV_INPUT_BUFFER_PADDING_SIZE);
nal->data = dst;
nal->size = di;
nal->raw_data = src;
nal->raw_size = si;
rbsp->rbsp_buffer_size += si;
return si;
}
static const char *const hevc_nal_type_name[64] = {
"TRAIL_N", // HEVC_NAL_TRAIL_N
"TRAIL_R", // HEVC_NAL_TRAIL_R
"TSA_N", // HEVC_NAL_TSA_N
"TSA_R", // HEVC_NAL_TSA_R
"STSA_N", // HEVC_NAL_STSA_N
"STSA_R", // HEVC_NAL_STSA_R
"RADL_N", // HEVC_NAL_RADL_N
"RADL_R", // HEVC_NAL_RADL_R
"RASL_N", // HEVC_NAL_RASL_N
"RASL_R", // HEVC_NAL_RASL_R
"RSV_VCL_N10", // HEVC_NAL_VCL_N10
"RSV_VCL_R11", // HEVC_NAL_VCL_R11
"RSV_VCL_N12", // HEVC_NAL_VCL_N12
"RSV_VLC_R13", // HEVC_NAL_VCL_R13
"RSV_VCL_N14", // HEVC_NAL_VCL_N14
"RSV_VCL_R15", // HEVC_NAL_VCL_R15
"BLA_W_LP", // HEVC_NAL_BLA_W_LP
"BLA_W_RADL", // HEVC_NAL_BLA_W_RADL
"BLA_N_LP", // HEVC_NAL_BLA_N_LP
"IDR_W_RADL", // HEVC_NAL_IDR_W_RADL
"IDR_N_LP", // HEVC_NAL_IDR_N_LP
"CRA_NUT", // HEVC_NAL_CRA_NUT
"RSV_IRAP_VCL22", // HEVC_NAL_RSV_IRAP_VCL22
"RSV_IRAP_VCL23", // HEVC_NAL_RSV_IRAP_VCL23
"RSV_VCL24", // HEVC_NAL_RSV_VCL24
"RSV_VCL25", // HEVC_NAL_RSV_VCL25
"RSV_VCL26", // HEVC_NAL_RSV_VCL26
"RSV_VCL27", // HEVC_NAL_RSV_VCL27
"RSV_VCL28", // HEVC_NAL_RSV_VCL28
"RSV_VCL29", // HEVC_NAL_RSV_VCL29
"RSV_VCL30", // HEVC_NAL_RSV_VCL30
"RSV_VCL31", // HEVC_NAL_RSV_VCL31
"VPS", // HEVC_NAL_VPS
"SPS", // HEVC_NAL_SPS
"PPS", // HEVC_NAL_PPS
"AUD", // HEVC_NAL_AUD
"EOS_NUT", // HEVC_NAL_EOS_NUT
"EOB_NUT", // HEVC_NAL_EOB_NUT
"FD_NUT", // HEVC_NAL_FD_NUT
"SEI_PREFIX", // HEVC_NAL_SEI_PREFIX
"SEI_SUFFIX", // HEVC_NAL_SEI_SUFFIX
"RSV_NVCL41", // HEVC_NAL_RSV_NVCL41
"RSV_NVCL42", // HEVC_NAL_RSV_NVCL42
"RSV_NVCL43", // HEVC_NAL_RSV_NVCL43
"RSV_NVCL44", // HEVC_NAL_RSV_NVCL44
"RSV_NVCL45", // HEVC_NAL_RSV_NVCL45
"RSV_NVCL46", // HEVC_NAL_RSV_NVCL46
"RSV_NVCL47", // HEVC_NAL_RSV_NVCL47
"UNSPEC48", // HEVC_NAL_UNSPEC48
"UNSPEC49", // HEVC_NAL_UNSPEC49
"UNSPEC50", // HEVC_NAL_UNSPEC50
"UNSPEC51", // HEVC_NAL_UNSPEC51
"UNSPEC52", // HEVC_NAL_UNSPEC52
"UNSPEC53", // HEVC_NAL_UNSPEC53
"UNSPEC54", // HEVC_NAL_UNSPEC54
"UNSPEC55", // HEVC_NAL_UNSPEC55
"UNSPEC56", // HEVC_NAL_UNSPEC56
"UNSPEC57", // HEVC_NAL_UNSPEC57
"UNSPEC58", // HEVC_NAL_UNSPEC58
"UNSPEC59", // HEVC_NAL_UNSPEC59
"UNSPEC60", // HEVC_NAL_UNSPEC60
"UNSPEC61", // HEVC_NAL_UNSPEC61
"UNSPEC62", // HEVC_NAL_UNSPEC62
"UNSPEC63", // HEVC_NAL_UNSPEC63
};
static const char *hevc_nal_unit_name(int nal_type)
{
av_assert0(nal_type >= 0 && nal_type < 64);
return hevc_nal_type_name[nal_type];
}
static const char *const h264_nal_type_name[32] = {
"Unspecified 0", //H264_NAL_UNSPECIFIED
"Coded slice of a non-IDR picture", // H264_NAL_SLICE
"Coded slice data partition A", // H264_NAL_DPA
"Coded slice data partition B", // H264_NAL_DPB
"Coded slice data partition C", // H264_NAL_DPC
"IDR", // H264_NAL_IDR_SLICE
"SEI", // H264_NAL_SEI
"SPS", // H264_NAL_SPS
"PPS", // H264_NAL_PPS
"AUD", // H264_NAL_AUD
"End of sequence", // H264_NAL_END_SEQUENCE
"End of stream", // H264_NAL_END_STREAM
"Filler data", // H264_NAL_FILLER_DATA
"SPS extension", // H264_NAL_SPS_EXT
"Prefix", // H264_NAL_PREFIX
"Subset SPS", // H264_NAL_SUB_SPS
"Depth parameter set", // H264_NAL_DPS
"Reserved 17", // H264_NAL_RESERVED17
"Reserved 18", // H264_NAL_RESERVED18
"Auxiliary coded picture without partitioning", // H264_NAL_AUXILIARY_SLICE
"Slice extension", // H264_NAL_EXTEN_SLICE
"Slice extension for a depth view or a 3D-AVC texture view", // H264_NAL_DEPTH_EXTEN_SLICE
"Reserved 22", // H264_NAL_RESERVED22
"Reserved 23", // H264_NAL_RESERVED23
"Unspecified 24", // H264_NAL_UNSPECIFIED24
"Unspecified 25", // H264_NAL_UNSPECIFIED25
"Unspecified 26", // H264_NAL_UNSPECIFIED26
"Unspecified 27", // H264_NAL_UNSPECIFIED27
"Unspecified 28", // H264_NAL_UNSPECIFIED28
"Unspecified 29", // H264_NAL_UNSPECIFIED29
"Unspecified 30", // H264_NAL_UNSPECIFIED30
"Unspecified 31", // H264_NAL_UNSPECIFIED31
};
static const char *h264_nal_unit_name(int nal_type)
{
av_assert0(nal_type >= 0 && nal_type < 32);
return h264_nal_type_name[nal_type];
}
static int get_bit_length(H2645NAL *nal, int min_size, int skip_trailing_zeros)
{
int size = nal->size;
int trailing_padding = 0;
while (skip_trailing_zeros && size > 0 && nal->data[size - 1] == 0)
size--;
if (!size)
return 0;
if (size <= min_size) {
if (nal->size < min_size)
return AVERROR_INVALIDDATA;
size = min_size;
} else {
int v = nal->data[size - 1];
/* remove the stop bit and following trailing zeros,
* or nothing for damaged bitstreams */
if (v)
trailing_padding = ff_ctz(v) + 1;
}
if (size > INT_MAX / 8)
return AVERROR(ERANGE);
size *= 8;
return size - trailing_padding;
}
/**
* @return AVERROR_INVALIDDATA if the packet is not a valid NAL unit,
* 0 otherwise
*/
static int hevc_parse_nal_header(H2645NAL *nal, void *logctx)
{
GetBitContext *gb = &nal->gb;
if (get_bits1(gb) != 0)
return AVERROR_INVALIDDATA;
nal->type = get_bits(gb, 6);
nal->nuh_layer_id = get_bits(gb, 6);
nal->temporal_id = get_bits(gb, 3) - 1;
if (nal->temporal_id < 0)
return AVERROR_INVALIDDATA;
av_log(logctx, AV_LOG_DEBUG,
"nal_unit_type: %d(%s), nuh_layer_id: %d, temporal_id: %d\n",
nal->type, hevc_nal_unit_name(nal->type), nal->nuh_layer_id, nal->temporal_id);
return 0;
}
static int h264_parse_nal_header(H2645NAL *nal, void *logctx)
{
GetBitContext *gb = &nal->gb;
if (get_bits1(gb) != 0)
return AVERROR_INVALIDDATA;
nal->ref_idc = get_bits(gb, 2);
nal->type = get_bits(gb, 5);
av_log(logctx, AV_LOG_DEBUG,
"nal_unit_type: %d(%s), nal_ref_idc: %d\n",
nal->type, h264_nal_unit_name(nal->type), nal->ref_idc);
return 0;
}
static int find_next_start_code(const uint8_t *buf, const uint8_t *next_avc)
{
int i = 0;
if (buf + 3 >= next_avc)
return next_avc - buf;
while (buf + i + 3 < next_avc) {
if (buf[i] == 0 && buf[i + 1] == 0 && buf[i + 2] == 1)
break;
i++;
}
return i + 3;
}
static void alloc_rbsp_buffer(H2645RBSP *rbsp, unsigned int size, int use_ref)
{
int min_size = size;
if (size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
goto fail;
size += AV_INPUT_BUFFER_PADDING_SIZE;
if (rbsp->rbsp_buffer_alloc_size >= size &&
(!rbsp->rbsp_buffer_ref || av_buffer_is_writable(rbsp->rbsp_buffer_ref))) {
av_assert0(rbsp->rbsp_buffer);
memset(rbsp->rbsp_buffer + min_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
return;
}
size = FFMIN(size + size / 16 + 32, INT_MAX);
if (rbsp->rbsp_buffer_ref)
av_buffer_unref(&rbsp->rbsp_buffer_ref);
else
av_free(rbsp->rbsp_buffer);
rbsp->rbsp_buffer = av_mallocz(size);
if (!rbsp->rbsp_buffer)
goto fail;
rbsp->rbsp_buffer_alloc_size = size;
if (use_ref) {
rbsp->rbsp_buffer_ref = av_buffer_create(rbsp->rbsp_buffer, size,
NULL, NULL, 0);
if (!rbsp->rbsp_buffer_ref)
goto fail;
}
return;
fail:
rbsp->rbsp_buffer_alloc_size = 0;
if (rbsp->rbsp_buffer_ref) {
av_buffer_unref(&rbsp->rbsp_buffer_ref);
rbsp->rbsp_buffer = NULL;
} else
av_freep(&rbsp->rbsp_buffer);
return;
}
int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
void *logctx, int is_nalff, int nal_length_size,
enum AVCodecID codec_id, int small_padding, int use_ref)
{
GetByteContext bc;
int consumed, ret = 0;
int next_avc = is_nalff ? 0 : length;
int64_t padding = small_padding ? 0 : MAX_MBPAIR_SIZE;
bytestream2_init(&bc, buf, length);
alloc_rbsp_buffer(&pkt->rbsp, length + padding, use_ref);
if (!pkt->rbsp.rbsp_buffer)
return AVERROR(ENOMEM);
pkt->rbsp.rbsp_buffer_size = 0;
pkt->nb_nals = 0;
while (bytestream2_get_bytes_left(&bc) >= 4) {
H2645NAL *nal;
int extract_length = 0;
int skip_trailing_zeros = 1;
if (bytestream2_tell(&bc) == next_avc) {
int i = 0;
extract_length = get_nalsize(nal_length_size,
bc.buffer, bytestream2_get_bytes_left(&bc), &i, logctx);
if (extract_length < 0)
return extract_length;
bytestream2_skip(&bc, nal_length_size);
next_avc = bytestream2_tell(&bc) + extract_length;
} else {
int buf_index;
if (bytestream2_tell(&bc) > next_avc)
av_log(logctx, AV_LOG_WARNING, "Exceeded next NALFF position, re-syncing.\n");
/* search start code */
buf_index = find_next_start_code(bc.buffer, buf + next_avc);
bytestream2_skip(&bc, buf_index);
if (!bytestream2_get_bytes_left(&bc)) {
if (pkt->nb_nals > 0) {
// No more start codes: we discarded some irrelevant
// bytes at the end of the packet.
return 0;
} else {
av_log(logctx, AV_LOG_ERROR, "No start code is found.\n");
return AVERROR_INVALIDDATA;
}
}
extract_length = FFMIN(bytestream2_get_bytes_left(&bc), next_avc - bytestream2_tell(&bc));
if (bytestream2_tell(&bc) >= next_avc) {
/* skip to the start of the next NAL */
bytestream2_skip(&bc, next_avc - bytestream2_tell(&bc));
continue;
}
}
if (pkt->nals_allocated < pkt->nb_nals + 1) {
int new_size = pkt->nals_allocated + 1;
void *tmp;
if (new_size >= INT_MAX / sizeof(*pkt->nals))
return AVERROR(ENOMEM);
tmp = av_fast_realloc(pkt->nals, &pkt->nal_buffer_size, new_size * sizeof(*pkt->nals));
if (!tmp)
return AVERROR(ENOMEM);
pkt->nals = tmp;
memset(pkt->nals + pkt->nals_allocated, 0, sizeof(*pkt->nals));
nal = &pkt->nals[pkt->nb_nals];
nal->skipped_bytes_pos_size = FFMIN(1024, extract_length/3+1); // initial buffer size
nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
if (!nal->skipped_bytes_pos)
return AVERROR(ENOMEM);
pkt->nals_allocated = new_size;
}
nal = &pkt->nals[pkt->nb_nals];
consumed = ff_h2645_extract_rbsp(bc.buffer, extract_length, &pkt->rbsp, nal, small_padding);
if (consumed < 0)
return consumed;
if (is_nalff && (extract_length != consumed) && extract_length)
av_log(logctx, AV_LOG_DEBUG,
"NALFF: Consumed only %d bytes instead of %d\n",
consumed, extract_length);
bytestream2_skip(&bc, consumed);
/* see commit 3566042a0 */
if (bytestream2_get_bytes_left(&bc) >= 4 &&
bytestream2_peek_be32(&bc) == 0x000001E0)
skip_trailing_zeros = 0;
nal->size_bits = get_bit_length(nal, 1 + (codec_id == AV_CODEC_ID_HEVC),
skip_trailing_zeros);
if (nal->size <= 0 || nal->size_bits <= 0)
continue;
ret = init_get_bits(&nal->gb, nal->data, nal->size_bits);
if (ret < 0)
return ret;
/* Reset type in case it contains a stale value from a previously parsed NAL */
nal->type = 0;
if (codec_id == AV_CODEC_ID_HEVC)
ret = hevc_parse_nal_header(nal, logctx);
else
ret = h264_parse_nal_header(nal, logctx);
if (ret < 0) {
av_log(logctx, AV_LOG_WARNING, "Invalid NAL unit %d, skipping.\n",
nal->type);
continue;
}
pkt->nb_nals++;
}
return 0;
}
void ff_h2645_packet_uninit(H2645Packet *pkt)
{
int i;
for (i = 0; i < pkt->nals_allocated; i++) {
av_freep(&pkt->nals[i].skipped_bytes_pos);
}
av_freep(&pkt->nals);
pkt->nals_allocated = pkt->nal_buffer_size = 0;
if (pkt->rbsp.rbsp_buffer_ref) {
av_buffer_unref(&pkt->rbsp.rbsp_buffer_ref);
pkt->rbsp.rbsp_buffer = NULL;
} else
av_freep(&pkt->rbsp.rbsp_buffer);
pkt->rbsp.rbsp_buffer_alloc_size = pkt->rbsp.rbsp_buffer_size = 0;
}
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