lib/mbedtls
1
0
Fork 0
mirror of https://github.com/Mbed-TLS/mbedtls.git synced 2025-07-30 22:43:08 +03:00
Code Activity

Avoid implementation defined behaviour

Browse Source 
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman
2023-09-12 12:38:53 +01:00
parent 49d7223036
commit bd58944252
1 changed files with 8 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
library/constant_time.c
View File

@ -130,7 +130,14 @@ int mbedtls_ct_memcmp(const void *a,
* This would have significant security implications, so protect against it. */
#error "mbedtls_ct_memcmp() requires minimum 32-bit ints"
#else
return (int) diff;
/* The bit-twiddling ensures that when we cast uint32_t to int, we are casting
* a value that is in the range 0..INT_MAX - a value larger than this would
* result in implementation defined behaviour.
*
* This ensures that the value returned by the function is non-zero iff
* diff is non-zero.
*/
return (int) ((diff & 0xffff) | (diff >> 16));
#endif
}