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Add some overflow checks for residual bits calculation

This commit is contained in:
Martijn van Beurden 2020-07-06 21:38:39 +02:00 committed by Erik de Castro Lopo
parent 38b7fec143
commit ced7f6829d
1 changed files with 15 additions and 8 deletions
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19
src/libFLAC/stream_encoder.c
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@ -4110,13 +4110,14 @@ static inline uint32_t count_rice_bits_in_partition_(
const FLAC__int32 *residual
)
{
uint32_t i, partition_bits =
uint32_t i;
uint64_t partition_bits =
FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN + /* actually could end up being FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2_PARAMETER_LEN but err on side of 16bps */
(1+rice_parameter) * partition_samples /* 1 for unary stop bit + rice_parameter for the binary portion */
;
for(i = 0; i < partition_samples; i++)
partition_bits += ( (FLAC__uint32)((residual[i]<<1)^(residual[i]>>31)) >> rice_parameter );
return partition_bits;
return (uint32_t)(flac_min(partition_bits,(uint32_t)(-1))); // To make sure the return value doesn't overflow
}
#else
static inline uint32_t count_rice_bits_in_partition_(
@ -4125,15 +4126,15 @@ static inline uint32_t count_rice_bits_in_partition_(
const FLAC__uint64 abs_residual_partition_sum
)
{
return
return (uint32_t)(flac_min( // To make sure the return value doesn't overflow
FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE_PARAMETER_LEN + /* actually could end up being FLAC__ENTROPY_CODING_METHOD_PARTITIONED_RICE2_PARAMETER_LEN but err on side of 16bps */
(1+rice_parameter) * partition_samples + /* 1 for unary stop bit + rice_parameter for the binary portion */
(
rice_parameter?
(uint32_t)(abs_residual_partition_sum >> (rice_parameter-1)) /* rice_parameter-1 because the real coder sign-folds instead of using a sign bit */
: (uint32_t)(abs_residual_partition_sum << 1) /* can't shift by negative number, so reverse */
(abs_residual_partition_sum >> (rice_parameter-1)) /* rice_parameter-1 because the real coder sign-folds instead of using a sign bit */
: (abs_residual_partition_sum << 1) /* can't shift by negative number, so reverse */
)
- (partition_samples >> 1)
- (partition_samples >> 1),(uint32_t)(-1)));
/* -(partition_samples>>1) to subtract out extra contributions to the abs_residual_partition_sum.
* The actual number of bits used is closer to the sum(for all i in the partition) of abs(residual[i])>>(rice_parameter-1)
* By using the abs_residual_partition sum, we also add in bits in the LSBs that would normally be shifted out.
@ -4224,7 +4225,10 @@ FLAC__bool set_partitioned_rice_(
raw_bits[0] = 0;
}
parameters[0] = best_rice_parameter;
if(best_partition_bits < UINT_MAX - bits_) // To make sure _bits doesn't overflow
bits_ += best_partition_bits;
else
bits_ = UINT_MAX;
}
else {
uint32_t partition, residual_sample;
@ -4327,7 +4331,10 @@ FLAC__bool set_partitioned_rice_(
raw_bits[partition] = 0;
}
parameters[partition] = best_rice_parameter;
if(best_partition_bits < UINT_MAX - bits_) // To make sure _bits doesn't overflow
bits_ += best_partition_bits;
else
bits_ = UINT_MAX;
residual_sample += partition_samples;
}
}