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ffmpeg
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golomb: use unsigned arithmetics in svq3_get_ue_golomb() 

This prevents undefined behaviour of signed left shift if the coded
value is larger than 2^31. Large values are most likely invalid and
caused errors or by feeding random.

Validate every use of svq3_get_ue_golomb() and changed the place there
the return value was compared with negative numbers. dirac.c was clean,
fixed rv30 and svq3.
This commit is contained in:
Janne Grunau 2012-11-30 15:00:47 +01:00
parent 1c012e6bfb
commit 9a2e79116d
3 changed files with 14 additions and 14 deletions
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5
libavcodec/golomb.h
View File

@ -107,7 +107,8 @@ static inline int get_ue_golomb_31(GetBitContext *gb){
return ff_ue_golomb_vlc_code[buf];
}
static inline int svq3_get_ue_golomb(GetBitContext *gb){
static inline unsigned svq3_get_ue_golomb(GetBitContext *gb)
{
uint32_t buf;
OPEN_READER(re, gb);
@ -121,7 +122,7 @@ static inline int svq3_get_ue_golomb(GetBitContext *gb){
return ff_interleaved_ue_golomb_vlc_code[buf];
}else{
int ret = 1;
unsigned ret = 1;
do {
buf >>= 32 - 8;

6
libavcodec/rv30.c
View File

@ -73,7 +73,7 @@ static int rv30_decode_intra_types(RV34DecContext *r, GetBitContext *gb, int8_t
for(i = 0; i < 4; i++, dst += r->intra_types_stride - 4){
for(j = 0; j < 4; j+= 2){
int code = svq3_get_ue_golomb(gb) << 1;
unsigned code = svq3_get_ue_golomb(gb) << 1;
if(code >= 81*2){
av_log(r->s.avctx, AV_LOG_ERROR, "Incorrect intra prediction code\n");
return -1;
@ -101,9 +101,9 @@ static int rv30_decode_mb_info(RV34DecContext *r)
static const int rv30_b_types[6] = { RV34_MB_SKIP, RV34_MB_B_DIRECT, RV34_MB_B_FORWARD, RV34_MB_B_BACKWARD, RV34_MB_TYPE_INTRA, RV34_MB_TYPE_INTRA16x16 };
MpegEncContext *s = &r->s;
GetBitContext *gb = &s->gb;
int code = svq3_get_ue_golomb(gb);
unsigned code = svq3_get_ue_golomb(gb);
if (code < 0 || code > 11) {
if (code > 11) {
av_log(s->avctx, AV_LOG_ERROR, "Incorrect MB type code\n");
return -1;
}

17
libavcodec/svq3.c
View File

@ -216,17 +216,15 @@ static inline int svq3_decode_block(GetBitContext *gb, DCTELEM *block,
static const uint8_t *const scan_patterns[4] =
{ luma_dc_zigzag_scan, zigzag_scan, svq3_scan, chroma_dc_scan };
int run, level, sign, vlc, limit;
int run, level, limit;
unsigned vlc;
const int intra = 3 * type >> 2;
const uint8_t *const scan = scan_patterns[type];
for (limit = (16 >> intra); index < 16; index = limit, limit += 8) {
for (; (vlc = svq3_get_ue_golomb(gb)) != 0; index++) {
if (vlc == INVALID_VLC)
return -1;
sign = (vlc & 0x1) - 1;
vlc = vlc + 1 >> 1;
int sign = (vlc & 1) ? 0 : -1;
vlc = vlc + 1 >> 1;
if (type == 3) {
if (vlc < 3) {
@ -786,7 +784,7 @@ static int svq3_decode_slice_header(AVCodecContext *avctx)
skip_bits_long(&s->gb, 0);
}
if ((i = svq3_get_ue_golomb(&s->gb)) == INVALID_VLC || i >= 3) {
if ((i = svq3_get_ue_golomb(&s->gb)) >= 3) {
av_log(h->s.avctx, AV_LOG_ERROR, "illegal slice type %d \n", i);
return -1;
}
@ -1010,7 +1008,7 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
H264Context *h = &svq3->h;
MpegEncContext *s = &h->s;
int buf_size = avpkt->size;
int m, mb_type;
int m;
/* special case for last picture */
if (buf_size == 0) {
@ -1093,6 +1091,7 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
for (s->mb_y = 0; s->mb_y < s->mb_height; s->mb_y++) {
for (s->mb_x = 0; s->mb_x < s->mb_width; s->mb_x++) {
unsigned mb_type;
h->mb_xy = s->mb_x + s->mb_y * s->mb_stride;
if ((get_bits_count(&s->gb) + 7) >= s->gb.size_in_bits &&
@ -1113,7 +1112,7 @@ static int svq3_decode_frame(AVCodecContext *avctx, void *data,
mb_type += 8;
else if (s->pict_type == AV_PICTURE_TYPE_B && mb_type >= 4)
mb_type += 4;
if ((unsigned)mb_type > 33 || svq3_decode_mb(svq3, mb_type)) {
if (mb_type > 33 || svq3_decode_mb(svq3, mb_type)) {
av_log(h->s.avctx, AV_LOG_ERROR,
"error while decoding MB %d %d\n", s->mb_x, s->mb_y);
return -1;