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Move size checks outside of mbedtls_platform_random_in_range

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Update the documentation to mention that calling it with zero
as an argument will result in an undefined behavior.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
This commit is contained in:
Andrzej Kurek 2020-11-02 15:53:39 +01:00
parent 8b0910a791
commit a138c0a0b0
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GPG key ID: 89A90840DC388527
2 changed files with 51 additions and 56 deletions
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103
library/platform_util.c
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@ -119,43 +119,45 @@ void *mbedtls_platform_zeroize( void *buf, size_t len )
void *mbedtls_platform_memset( void *ptr, int value, size_t num )
{
size_t i, start_offset;
size_t i, start_offset = 0;
volatile size_t flow_counter = 0;
volatile char *b = ptr;
char rnd_data;
start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
rnd_data = (char) mbedtls_platform_random_in_range( 256 );
/* Perform a memset operations with random data and start from a random
* location */
for( i = start_offset; i < num; ++i )
if( num > 0 )
{
b[i] = rnd_data;
flow_counter++;
}
start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
/* Start from a random location with target data */
for( i = start_offset; i < num; ++i )
{
b[i] = value;
flow_counter++;
}
rnd_data = (char) mbedtls_platform_random_in_range( 256 );
/* Second memset operation with random data */
for( i = 0; i < start_offset; ++i )
{
b[i] = rnd_data;
flow_counter++;
}
/* Perform a memset operations with random data and start from a random
* location */
for( i = start_offset; i < num; ++i )
{
b[i] = rnd_data;
flow_counter++;
}
/* Finish memset operation with correct data */
for( i = 0; i < start_offset; ++i )
{
b[i] = value;
flow_counter++;
}
/* Start from a random location with target data */
for( i = start_offset; i < num; ++i )
{
b[i] = value;
flow_counter++;
}
/* Second memset operation with random data */
for( i = 0; i < start_offset; ++i )
{
b[i] = rnd_data;
flow_counter++;
}
/* Finish memset operation with correct data */
for( i = 0; i < start_offset; ++i )
{
b[i] = value;
flow_counter++;
}
}
/* check the correct number of iterations */
if( flow_counter == 2 * num )
{
@ -165,6 +167,7 @@ void *mbedtls_platform_memset( void *ptr, int value, size_t num )
return ptr;
}
}
return NULL;
}
@ -245,22 +248,25 @@ int mbedtls_platform_memequal( const void *buf1, const void *buf2, size_t num )
/* Start from a random location and check the correct number of iterations */
size_t i, flow_counter = 0;
size_t start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
for( i = start_offset; i < num; i++ )
size_t start_offset = 0;
if( num > 0 )
{
unsigned char x = A[i], y = B[i];
flow_counter++;
diff |= x ^ y;
}
start_offset = (size_t) mbedtls_platform_random_in_range( (uint32_t) num );
for( i = 0; i < start_offset; i++ )
{
unsigned char x = A[i], y = B[i];
flow_counter++;
diff |= x ^ y;
}
for( i = start_offset; i < num; i++ )
{
unsigned char x = A[i], y = B[i];
flow_counter++;
diff |= x ^ y;
}
for( i = 0; i < start_offset; i++ )
{
unsigned char x = A[i], y = B[i];
flow_counter++;
diff |= x ^ y;
}
}
/* Return 0 only when diff is 0 and flow_counter is equal to num */
return( (int) diff | (int) ( flow_counter ^ num ) );
}
@ -340,18 +346,7 @@ void mbedtls_platform_random_buf( uint8_t *buf, size_t len )
uint32_t mbedtls_platform_random_in_range( uint32_t num )
{
uint32_t result;
if( num <= 1 )
{
result = 0;
}
else
{
result = mbedtls_platform_random_uint32() % num;
}
return( result );
return mbedtls_platform_random_uint32() % num;
}
void mbedtls_platform_random_delay( void )