yuzu/mbedtls
1
0
Fork 0
mirror of https://github.com/yuzu-emu/mbedtls.git synced 2025-01-23 16:51:08 +00:00
Code Issues Packages Projects Releases Wiki Activity

Use bitwise comparison in memcmp

Browse source 
It is safer than == operator.
This commit is contained in:
Jarno Lamsa 2019-10-02 08:32:51 +03:00
parent 32db938463
commit 7cb902737b
1 changed files with 8 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
library/platform_util.c
View file

@ -112,7 +112,9 @@ void mbedtls_platform_memcpy( void *dst, const void *src, size_t num )
int mbedtls_platform_memcmp( const void *buf1, const void *buf2, size_t num ) int mbedtls_platform_memcmp( const void *buf1, const void *buf2, size_t num )
{ {
volatile unsigned int equal = 0; volatile const unsigned char *A = (volatile const unsigned char *) buf1;
volatile const unsigned char *B = (volatile const unsigned char *) buf2;
volatile unsigned char diff = 0;
size_t i = num; size_t i = num;
@ -120,22 +122,17 @@ int mbedtls_platform_memcmp( const void *buf1, const void *buf2, size_t num )
for( i = start_offset; i < num; i++ ) for( i = start_offset; i < num; i++ )
{ {
equal += ( ( (unsigned char *) buf1 )[i] == unsigned char x = A[i], y = B[i];
( (unsigned char *) buf2 )[i] ); diff |= x ^ y;
} }
for( i = 0; i < start_offset; i++ ) for( i = 0; i < start_offset; i++ )
{ {
equal += ( ( (unsigned char *) buf1 )[i] == unsigned char x = A[i], y = B[i];
( (unsigned char *) buf2 )[i] ); diff |= x ^ y;
} }
if ( equal == num ) return( diff );
{
return 0;
}
return 1;
} }
#if !defined(MBEDTLS_PLATFORM_GLOBAL_RNG) #if !defined(MBEDTLS_PLATFORM_GLOBAL_RNG)