This memset() in the ubsec ENGINE is a bug. Zeroing out the result array

should not be necessary in any case, but more importantly the result and
input BIGNUMs could be the same, in which case this is clearly a problem.

Submitted by: Jonathan Hersch
Reviewed by: Joe Orton
Approved by: Geoff Thorpe

engines/e_ubsec.c

@@ -566,7 +566,6 @@ static int ubsec_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
 		UBSECerr(UBSEC_F_UBSEC_MOD_EXP, UBSEC_R_BN_EXPAND_FAIL);
 		return 0;
 	}
-	memset(r->d, 0, BN_num_bytes(m));
 
 	if ((fd = p_UBSEC_ubsec_open(UBSEC_KEY_DEVICE_NAME)) <= 0) {
 		fd = 0;