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snow: check reference frame indices. 

Fixes NULL ptr dereference

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-03-02 20:53:00 +01:00
parent 8fdd93eaad
commit 0af48e29f5
1 changed files with 21 additions and 9 deletions
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30
libavcodec/snowdec.c
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@ -132,7 +132,7 @@ static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, sli
return;
}
static void decode_q_branch(SnowContext *s, int level, int x, int y){
static int decode_q_branch(SnowContext *s, int level, int x, int y){
const int w= s->b_width << s->block_max_depth;
const int rem_depth= s->block_max_depth - level;
const int index= (x + y*w) << rem_depth;
@ -145,7 +145,7 @@ static void decode_q_branch(SnowContext *s, int level, int x, int y){
if(s->keyframe){
set_blocks(s, level, x, y, null_block.color[0], null_block.color[1], null_block.color[2], null_block.mx, null_block.my, null_block.ref, BLOCK_INTRA);
return;
return 0;
}
if(level==s->block_max_depth || get_rac(&s->c, &s->block_state[4 + s_context])){
@ -168,17 +168,26 @@ static void decode_q_branch(SnowContext *s, int level, int x, int y){
}else{
if(s->ref_frames > 1)
ref= get_symbol(&s->c, &s->block_state[128 + 1024 + 32*ref_context], 0);
if (ref >= s->ref_frames) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid ref\n");
return -1;
}
pred_mv(s, &mx, &my, ref, left, top, tr);
mx+= get_symbol(&s->c, &s->block_state[128 + 32*(mx_context + 16*!!ref)], 1);
my+= get_symbol(&s->c, &s->block_state[128 + 32*(my_context + 16*!!ref)], 1);
}
set_blocks(s, level, x, y, l, cb, cr, mx, my, ref, type);
}else{
decode_q_branch(s, level+1, 2*x+0, 2*y+0);
decode_q_branch(s, level+1, 2*x+1, 2*y+0);
decode_q_branch(s, level+1, 2*x+0, 2*y+1);
decode_q_branch(s, level+1, 2*x+1, 2*y+1);
if (decode_q_branch(s, level+1, 2*x+0, 2*y+0)<0)
return -1;
if (decode_q_branch(s, level+1, 2*x+1, 2*y+0)<0)
return -1;
if (decode_q_branch(s, level+1, 2*x+0, 2*y+1)<0)
return -1;
if (decode_q_branch(s, level+1, 2*x+1, 2*y+1)<0)
return -1;
}
return 0;
}
static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
@ -349,16 +358,18 @@ static av_cold int decode_init(AVCodecContext *avctx)
return 0;
}
static void decode_blocks(SnowContext *s){
static int decode_blocks(SnowContext *s){
int x, y;
int w= s->b_width;
int h= s->b_height;
for(y=0; y<h; y++){
for(x=0; x<w; x++){
decode_q_branch(s, 0, x, y);
if (decode_q_branch(s, 0, x, y) < 0)
return -1;
}
}
return 0;
}
static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt){
@ -397,7 +408,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPac
if(avctx->debug&FF_DEBUG_PICT_INFO)
av_log(avctx, AV_LOG_ERROR, "keyframe:%d qlog:%d\n", s->keyframe, s->qlog);
decode_blocks(s);
if (decode_blocks(s) < 0)
return -1;
for(plane_index=0; plane_index<3; plane_index++){
Plane *p= &s->plane[plane_index];