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harden h264 decoding to prevent some crashes when input data is corrupted.

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Patch by Frank %eucloid A gmail P com%
date: Jan 18, 2007 6:48 PM
subject: Re: [Ffmpeg-devel] h264, protection against corrupted data (second try patch)
AND
date: Jan 17, 2007 8:22 PM
subject: [Ffmpeg-devel] h264, protection against corrupted data

this also fixes a possible security issue (the sps and pps ids where not checked,
then used as index into an array of sps/pps structs which was then filled with data from the bitstream)

Originally committed as revision 7585 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Francois Oligny-Lemieux 2007-01-19 09:37:04 +00:00 committed by Guillaume Poirier
parent 045bdb5ab4
commit ac658be5db
1 changed files with 46 additions and 19 deletions
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65
libavcodec/h264.c
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@ -117,7 +117,7 @@ typedef struct SPS{
* Picture parameter set
*/
typedef struct PPS{
int sps_id;
unsigned int sps_id;
int cabac; ///< entropy_coding_mode_flag
int pic_order_present; ///< pic_order_present_flag
int slice_group_count; ///< num_slice_groups_minus1 + 1
@ -1780,6 +1780,10 @@ static uint8_t *decode_nal(H264Context *h, uint8_t *src, int *dst_length, int *c
h->rbsp_buffer= av_fast_realloc(h->rbsp_buffer, &h->rbsp_buffer_size, length);
dst= h->rbsp_buffer;
if (dst == NULL){
return NULL;
}
//printf("decoding esc\n");
si=di=0;
while(si<length){
@ -3950,10 +3954,14 @@ static int decode_ref_pic_list_reordering(H264Context *h){
}else{
pic_id= get_ue_golomb(&s->gb); //long_term_pic_idx
ref = h->long_ref[pic_id];
ref->pic_id= pic_id;
assert(ref->reference == 3);
assert(ref->long_ref);
i=0;
if(ref){
ref->pic_id= pic_id;
assert(ref->reference == 3);
assert(ref->long_ref);
i=0;
}else{
i=-1;
}
}
if (i < 0) {
@ -4259,8 +4267,10 @@ static int execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count){
if(pic) unreference_pic(h, pic);
h->long_ref[ mmco[i].long_index ]= remove_short(h, mmco[i].short_frame_num);
h->long_ref[ mmco[i].long_index ]->long_ref=1;
h->long_ref_count++;
if (h->long_ref[ mmco[i].long_index ]){
h->long_ref[ mmco[i].long_index ]->long_ref=1;
h->long_ref_count++;
}
break;
case MMCO_LONG2UNUSED:
pic= remove_long(h, mmco[i].long_index);
@ -4290,7 +4300,7 @@ static int execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count){
case MMCO_RESET:
while(h->short_ref_count){
pic= remove_short(h, h->short_ref[0]->frame_num);
unreference_pic(h, pic);
if(pic) unreference_pic(h, pic);
}
for(j = 0; j < 16; j++) {
pic= remove_long(h, j);
@ -4473,7 +4483,8 @@ static int init_poc(H264Context *h){
*/
static int decode_slice_header(H264Context *h){
MpegEncContext * const s = &h->s;
int first_mb_in_slice, pps_id;
int first_mb_in_slice;
unsigned int pps_id;
int num_ref_idx_active_override_flag;
static const uint8_t slice_type_map[5]= {P_TYPE, B_TYPE, I_TYPE, SP_TYPE, SI_TYPE};
int slice_type;
@ -4505,7 +4516,7 @@ static int decode_slice_header(H264Context *h){
s->pict_type= h->slice_type; // to make a few old func happy, it's wrong though
pps_id= get_ue_golomb(&s->gb);
if(pps_id>255){
if(pps_id>=MAX_PPS_COUNT){
av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
return -1;
}
@ -4521,8 +4532,8 @@ static int decode_slice_header(H264Context *h){
return -1;
}
if(h->dequant_coeff_pps != pps_id){
h->dequant_coeff_pps = pps_id;
if(h->dequant_coeff_pps != (int)pps_id){
h->dequant_coeff_pps = (int)pps_id;
init_dequant_tables(h);
}
@ -4762,7 +4773,7 @@ static int decode_slice_header(H264Context *h){
h->emu_edge_height= FRAME_MBAFF ? 0 : h->emu_edge_width;
if(s->avctx->debug&FF_DEBUG_PICT_INFO){
av_log(h->s.avctx, AV_LOG_DEBUG, "slice:%d %s mb:%d %c pps:%d frame:%d poc:%d/%d ref:%d/%d qp:%d loop:%d:%d:%d weight:%d%s\n",
av_log(h->s.avctx, AV_LOG_DEBUG, "slice:%d %s mb:%d %c pps:%u frame:%d poc:%d/%d ref:%d/%d qp:%d loop:%d:%d:%d weight:%d%s\n",
h->slice_num,
(s->picture_structure==PICT_FRAME ? "F" : s->picture_structure==PICT_TOP_FIELD ? "T" : "B"),
first_mb_in_slice,
@ -7672,7 +7683,8 @@ static void decode_scaling_matrices(H264Context *h, SPS *sps, PPS *pps, int is_s
static inline int decode_seq_parameter_set(H264Context *h){
MpegEncContext * const s = &h->s;
int profile_idc, level_idc;
int sps_id, i;
unsigned int sps_id;
int i;
SPS *sps;
profile_idc= get_bits(&s->gb, 8);
@ -7684,6 +7696,12 @@ static inline int decode_seq_parameter_set(H264Context *h){
level_idc= get_bits(&s->gb, 8);
sps_id= get_ue_golomb(&s->gb);
if (sps_id >= MAX_SPS_COUNT){
// ok it has gone out of hand, someone is sending us bad stuff.
av_log(h->s.avctx, AV_LOG_ERROR, "illegal sps_id (%d)\n", sps_id);
return -1;
}
sps= &h->sps_buffer[ sps_id ];
sps->profile_idc= profile_idc;
sps->level_idc= level_idc;
@ -7764,7 +7782,7 @@ static inline int decode_seq_parameter_set(H264Context *h){
decode_vui_parameters(h, sps);
if(s->avctx->debug&FF_DEBUG_PICT_INFO){
av_log(h->s.avctx, AV_LOG_DEBUG, "sps:%d profile:%d/%d poc:%d ref:%d %dx%d %s %s crop:%d/%d/%d/%d %s\n",
av_log(h->s.avctx, AV_LOG_DEBUG, "sps:%u profile:%d/%d poc:%d ref:%d %dx%d %s %s crop:%d/%d/%d/%d %s\n",
sps_id, sps->profile_idc, sps->level_idc,
sps->poc_type,
sps->ref_frame_count,
@ -7781,8 +7799,14 @@ static inline int decode_seq_parameter_set(H264Context *h){
static inline int decode_picture_parameter_set(H264Context *h, int bit_length){
MpegEncContext * const s = &h->s;
int pps_id= get_ue_golomb(&s->gb);
PPS *pps= &h->pps_buffer[pps_id];
unsigned int pps_id= get_ue_golomb(&s->gb);
PPS *pps;
if(pps_id>=MAX_PPS_COUNT){
av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");
return -1;
}
pps = &h->pps_buffer[pps_id];
pps->sps_id= get_ue_golomb(&s->gb);
pps->cabac= get_bits1(&s->gb);
@ -7853,7 +7877,7 @@ static inline int decode_picture_parameter_set(H264Context *h, int bit_length){
}
if(s->avctx->debug&FF_DEBUG_PICT_INFO){
av_log(h->s.avctx, AV_LOG_DEBUG, "pps:%d sps:%d %s slice_groups:%d ref:%d/%d %s qp:%d/%d/%d %s %s %s %s\n",
av_log(h->s.avctx, AV_LOG_DEBUG, "pps:%u sps:%u %s slice_groups:%d ref:%d/%d %s qp:%d/%d/%d %s %s %s %s\n",
pps_id, pps->sps_id,
pps->cabac ? "CABAC" : "CAVLC",
pps->slice_group_count,
@ -7987,7 +8011,7 @@ static int decode_nal_units(H264Context *h, uint8_t *buf, int buf_size){
nalsize = 0;
for(i = 0; i < h->nal_length_size; i++)
nalsize = (nalsize << 8) | buf[buf_index++];
if(nalsize <= 1){
if(nalsize <= 1 || nalsize > buf_size){
if(nalsize == 1){
buf_index++;
continue;
@ -8010,6 +8034,9 @@ static int decode_nal_units(H264Context *h, uint8_t *buf, int buf_size){
}
ptr= decode_nal(h, buf + buf_index, &dst_length, &consumed, h->is_avc ? nalsize : buf_size - buf_index);
if (ptr==NULL || dst_length <= 0){
return -1;
}
while(ptr[dst_length - 1] == 0 && dst_length > 1)
dst_length--;
bit_length= 8*dst_length - decode_rbsp_trailing(ptr + dst_length - 1);