evm: Fix possible memory leak in evm_calc_hmac_or_hash()

Don't immediately return if the signature is portable and security.ima is
not present. Just set error so that memory allocated is freed before
returning from evm_calc_hmac_or_hash().

Fixes: 50b977481f ("EVM: Add support for portable signature format")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity/evm/evm_crypto.c

@@ -241,7 +241,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry,
 
 	/* Portable EVM signatures must include an IMA hash */
 	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
-		return -EPERM;
+		error = -EPERM;
 out:
 	kfree(xattr_value);
 	kfree(desc);