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alsdec: check block length 

Fix writing over the end

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-12-12 12:28:45 +01:00
parent 16c3cb9bbf
commit 0ceca269b6
1 changed files with 8 additions and 2 deletions
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10
libavcodec/alsdec.c
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@ -553,12 +553,15 @@ static void get_block_sizes(ALSDecContext *ctx, unsigned int *div_blocks,
/** Read the block data for a constant block
*/
static void read_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)
static int read_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)
{
ALSSpecificConfig *sconf = &ctx->sconf;
AVCodecContext *avctx = ctx->avctx;
GetBitContext *gb = &ctx->gb;
if (bd->block_length <= 0)
return -1;
*bd->raw_samples = 0;
*bd->const_block = get_bits1(gb); // 1 = constant value, 0 = zero block (silence)
bd->js_blocks = get_bits1(gb);
@ -573,6 +576,8 @@ static void read_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)
// ensure constant block decoding by reusing this field
*bd->const_block = 1;
return 0;
}
@ -972,7 +977,8 @@ static int read_block(ALSDecContext *ctx, ALSBlockData *bd)
if (read_var_block_data(ctx, bd))
return -1;
} else {
read_const_block_data(ctx, bd);
if (read_const_block_data(ctx, bd) < 0)
return -1;
}
return 0;