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Add some overflow checks for residual bits calculation

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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 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 */ 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 */ (1+rice_parameter) * partition_samples /* 1 for unary stop bit + rice_parameter for the binary portion */
; ;
for(i = 0; i < partition_samples; i++) for(i = 0; i < partition_samples; i++)
partition_bits += ( (FLAC__uint32)((residual[i]<<1)^(residual[i]>>31)) >> rice_parameter ); 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 #else
static inline uint32_t count_rice_bits_in_partition_( 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 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 */ 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 */ (1+rice_parameter) * partition_samples + /* 1 for unary stop bit + rice_parameter for the binary portion */
( (
rice_parameter? 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 */ (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 << 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. /* -(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) * 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. * 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; raw_bits[0] = 0;
} }
parameters[0] = best_rice_parameter; parameters[0] = best_rice_parameter;
if(best_partition_bits < UINT_MAX - bits_) // To make sure _bits doesn't overflow
bits_ += best_partition_bits; bits_ += best_partition_bits;
else
bits_ = UINT_MAX;
} }
else { else {
uint32_t partition, residual_sample; uint32_t partition, residual_sample;
@@ -4327,7 +4331,10 @@ FLAC__bool set_partitioned_rice_(
raw_bits[partition] = 0; raw_bits[partition] = 0;
} }
parameters[partition] = best_rice_parameter; parameters[partition] = best_rice_parameter;
if(best_partition_bits < UINT_MAX - bits_) // To make sure _bits doesn't overflow
bits_ += best_partition_bits; bits_ += best_partition_bits;
else
bits_ = UINT_MAX;
residual_sample += partition_samples; residual_sample += partition_samples;
} }
} }