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avcodec/rpza: Perform pointer advance and checks before using the poi…

…nters

Fixes out of array accesses
Fixes Ticket2850

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
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michaelni committed Aug 21, 2013
1 parent 920046a commit 3819db745da2ac7fb3faacb116788c32f4753f34
Showing with 4 additions and 4 deletions.
  1. +4 −4 libavcodec/rpza.c
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@@ -85,7 +85,7 @@ static void rpza_decode_stream(RpzaContext *s)
unsigned short *pixels = (unsigned short *)s->frame.data[0];
int row_ptr = 0;
- int pixel_ptr = 0;
+ int pixel_ptr = -4;
int block_ptr;
int pixel_x, pixel_y;
int total_blocks;
@@ -141,6 +141,7 @@ static void rpza_decode_stream(RpzaContext *s)
colorA = AV_RB16 (&s->buf[stream_ptr]);
stream_ptr += 2;
while (n_blocks--) {
+ ADVANCE_BLOCK()
block_ptr = row_ptr + pixel_ptr;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++){
@@ -149,7 +150,6 @@ static void rpza_decode_stream(RpzaContext *s)
}
block_ptr += row_inc;
}
- ADVANCE_BLOCK();
}
break;
@@ -188,6 +188,7 @@ static void rpza_decode_stream(RpzaContext *s)
if (s->size - stream_ptr < n_blocks * 4)
return;
while (n_blocks--) {
+ ADVANCE_BLOCK();
block_ptr = row_ptr + pixel_ptr;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
index = s->buf[stream_ptr++];
@@ -198,14 +199,14 @@ static void rpza_decode_stream(RpzaContext *s)
}
block_ptr += row_inc;
}
- ADVANCE_BLOCK();
}
break;
/* Fill block with 16 colors */
case 0x00:
if (s->size - stream_ptr < 16)
return;
+ ADVANCE_BLOCK();
block_ptr = row_ptr + pixel_ptr;
for (pixel_y = 0; pixel_y < 4; pixel_y++) {
for (pixel_x = 0; pixel_x < 4; pixel_x++){
@@ -219,7 +220,6 @@ static void rpza_decode_stream(RpzaContext *s)
}
block_ptr += row_inc;
}
- ADVANCE_BLOCK();
break;
/* Unknown opcode */

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