Catch AES failure in mbedtls_ctr_drbg_random
The functions mbedtls_ctr_drbg_random() and
mbedtls_ctr_drbg_random_with_add() could return 0 if an AES function
failed. This could only happen with alternative AES
implementations (the built-in implementation of the AES functions
involved never fail), typically due to a failure in a hardware
accelerator.
Bug reported and fix proposed by Johan Uppman Bruce and Christoffer
Lauri, Sectra.
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 047bb2a..517b455 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -584,7 +584,7 @@
exit:
mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
- return( 0 );
+ return( ret );
}
int mbedtls_ctr_drbg_random( void *p_rng, unsigned char *output,