linux-kernel - Re: [PATCH] crypto: initialize error variable

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Date:   Mon, 16 Aug 2021 15:01:19 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     trix@...hat.com, brijesh.singh@....com, john.allen@....com,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        ashish.kalra@....com, rientjes@...gle.com
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] crypto: initialize error variable

On 8/16/21 2:23 PM, trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
> 
> Static analysis reports this problem
> sev-dev.c:1094:19: warning: The left operand of '==' is a garbage value
>         if (rc && (error == SEV_RET_SECURE_DATA_INVALID)) {
>                    ~~~~~ ^
> 
> The error variable may not be set by the call to
> sev_platform_init().  So initialize error to SEV_RET_SUCCESS.
> 
> Fixes: 1d55fdc85799 ("crypto: ccp - Retry SEV INIT command in case of integrity check failure.")
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/crypto/ccp/sev-dev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 2ecb0e1f65d8d..b2b9f0f4daf2d 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1065,7 +1065,7 @@ void sev_pci_init(void)
>  {
>  	struct sev_device *sev = psp_master->sev_data;
>  	struct page *tmr_page;
> -	int error, rc;
> +	int error = SEV_RET_SUCCESS, rc;

Looking ahead to recently submitted SEV-SNP patches that will also use the
error variable (and will also need to initialize it), lets move the
initialization of error to just before the call to sev_platform_init() so
it doesn't end up with a possible stale value in the future:

https://lore.kernel.org/lkml/20210707183616.5620-13-brijesh.singh@amd.com/

Thanks,
Tom

>  
>  	if (!sev)
>  		return;
>