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Merge pull request #3403 from piotr-now/sca_memmove

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Add mbedtls_platform_memmove() as a secured memcmp()
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Piotr Nowicki 2020-06-10 14:52:02 +02:00 • committed by GitHub
commit f523c47578
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9 changed files with 67 additions and 7 deletions
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23
library/platform_util.c
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@ -38,6 +38,12 @@
#include "mbedtls/platform.h"
#include "mbedtls/threading.h"
#if !defined(MBEDTLS_PLATFORM_C)
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#if defined(MBEDTLS_ENTROPY_HARDWARE_ALT)
#include "mbedtls/entropy_poll.h"
#endif
@ -121,6 +127,23 @@ void *mbedtls_platform_memcpy( void *dst, const void *src, size_t num )
return( memcpy( (void *) dst, (void *) src, start_offset ) );
}
int mbedtls_platform_memmove( void *dst, const void *src, size_t num )
{
/* The buffers can have a common part, so we cannot do a copy from a random
* location. By using a temporary buffer we can do so, but the cost of it
* is using more memory and longer transfer time. */
void *tmp = mbedtls_calloc( 1, num );
if( tmp != NULL )
{
mbedtls_platform_memcpy( tmp, src, num );
mbedtls_platform_memcpy( dst, tmp, num );
mbedtls_free( tmp );
return 0;
}
return MBEDTLS_ERR_PLATFORM_ALLOC_FAILED;
}
int mbedtls_platform_memcmp( const void *buf1, const void *buf2, size_t num )
{
volatile const unsigned char *A = (volatile const unsigned char *) buf1;