linux-kernel - Re: [PATCH] keys: asymmetric: fix error return code in software_key

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Message-ID: <20200723013223.GA45081@linux.intel.com>
Date:   Thu, 23 Jul 2020 04:32:35 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     David Howells <dhowells@...hat.com>
Cc:     torvalds@...ux-foundation.org,
        Wei Yongjun <weiyongjun1@...wei.com>, keyrings@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] keys: asymmetric: fix error return code in
 software_key_query()

On Wed, Jul 15, 2020 at 11:28:38PM +0100, David Howells wrote:
> From: Wei Yongjun <weiyongjun1@...wei.com>
> 
> Fix to return negative error code -ENOMEM from kmalloc() error handling
> case instead of 0, as done elsewhere in this function.
> 
> Fixes: f1774cb8956a ("X.509: parse public key parameters from x509 for akcipher")
> Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
> Signed-off-by: David Howells <dhowells@...hat.com>

Why f1774cb8956a lacked any possible testing? It extends ABI anyway.

I think it is a kind of change that would require more screening before
getting applied.

> ---
> 
>  crypto/asymmetric_keys/public_key.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index d7f43d4ea925..e5fae4e838c0 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -119,6 +119,7 @@ static int software_key_query(const struct kernel_pkey_params *params,
>  	if (IS_ERR(tfm))
>  		return PTR_ERR(tfm);
>  
> +	ret = -ENOMEM;

This is extremely confusing to read way to handle 'ret'.

Would be way more cleaner to be just simple and stupid:

	if (!key) {
		ret = -ENOMEM;
		goto error_free_tfm;
	}

>  	key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
>  		      GFP_KERNEL);
>  	if (!key)

/Jarkko