Re: [PATCH v5 4/4] powerpc: load firmware trusted keys/hashes into kernel keyring

From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Nayna Jain <nayna@linux.ibm.com>,
	linuxppc-dev@ozlabs.org, linux-efi@vger.kernel.org,
	linux-integrity@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jeremy Kerr <jk@ozlabs.org>,
	Matthew Garret <matthew.garret@nebula.com>,
	Mimi Zohar <zohar@linux.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Claudio Carvalho <cclaudio@linux.ibm.com>,
	George Wilson <gcwilson@linux.ibm.com>,
	Elaine Palmer <erpalmer@us.ibm.com>,
	Eric Ricther <erichte@linux.ibm.com>,
	Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH v5 4/4] powerpc: load firmware trusted keys/hashes into kernel keyring
Date: Fri, 25 Oct 2019 09:02:47 -0700	[thread overview]
Message-ID: <5be98aad-66b9-2549-2772-ef30aa1275b4@linux.microsoft.com> (raw)
In-Reply-To: <20191025005839.4498-1-nayna@linux.ibm.com>

On 10/24/19 5:58 PM, Nayna Jain wrote:

> +
> +/*
> + * Get a certificate list blob from the named secure variable.
> + */
> +static __init void *get_cert_list(u8 *key, unsigned long keylen, uint64_t *size)
> +{
> +	int rc;
> +	void *db;
> +
> +	rc = secvar_ops->get(key, keylen, NULL, size);
> +	if (rc) {
> +		pr_err("Couldn't get size: %d\n", rc);
> +		return NULL;
> +	}
> +
> +	db = kmalloc(*size, GFP_KERNEL);

Is there a MIN\MAX limit on size that should be validated here before 
memory allocation?

> +	if (!db)
> +		return NULL;
> +
> +	rc = secvar_ops->get(key, keylen, db, size);
> +	if (rc) {
> +		kfree(db);
> +		pr_err("Error reading db var: %d\n", rc);
> +		return NULL;
nit: set db to NULL and return from the end of the function.

> +	}
> +
> +	return db;
> +}