linux-kernel - Re: [PATCH] tpm: return -ENODEV if np is not set

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Date:   Tue, 15 Nov 2016 09:33:53 -0800
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Colin King <colin.king@...onical.com>
Cc:     Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm: return -ENODEV if np is not set

On Tue, Nov 15, 2016 at 01:27:22PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> device_node np contains a garbage value from the stack and it
> is only set if chip->dev.parent->of_node is not null.  Thus the
> check for a null np won't spot a garbage value of np from the
> stack if chip->dev.parent->of_node is null and if np contains
> an garbage non-null value.
> 
> I believe the correct fix is to return -ENODEV if and only if
> chip->dev.parent->of_node is null.
> 
> Found with static analysis by CoverityScan, CID 1377755
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

/Jarkko

> ---
>  drivers/char/tpm/tpm_of.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 3af829f..1426590 100644
> --- a/drivers/char/tpm/tpm_of.c
> +++ b/drivers/char/tpm/tpm_of.c
> @@ -31,7 +31,7 @@ int read_log_of(struct tpm_chip *chip)
>  	log = &chip->log;
>  	if (chip->dev.parent->of_node)
>  		np = chip->dev.parent->of_node;
> -	if (!np)
> +	else
>  		return -ENODEV;
>  
>  	sizep = of_get_property(np, "linux,sml-size", NULL);
> -- 
> 2.10.2
>