linux-kernel - Re: [PATCH] char: tmp: fix potential null pointer dereference

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Message-ID: <20170531121129.f3576lq7peott6gd@intel.com>
Date:   Wed, 31 May 2017 15:11:29 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.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] char: tmp: fix potential null pointer dereference

On Tue, May 30, 2017 at 04:51:23PM -0500, Gustavo A. R. Silva wrote:
> NULL check at line 147: if (chip) {, implies chip might be NULL.
> Function dev_get_drvdata() dereference pointer chip.
> Move pointer priv assignment inside the IF block that checks
> pointer chip.
> 
> Addresses-Coverity-ID: 1397646
> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>

It cannot be.

/Jarkko

> ---
>  drivers/char/tpm/tpm_atmel.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm_atmel.c b/drivers/char/tpm/tpm_atmel.c
> index 0d322ab..0826efd 100644
> --- a/drivers/char/tpm/tpm_atmel.c
> +++ b/drivers/char/tpm/tpm_atmel.c
> @@ -142,9 +142,10 @@ static struct platform_device *pdev;
>  static void atml_plat_remove(void)
>  {
>  	struct tpm_chip *chip = dev_get_drvdata(&pdev->dev);
> -	struct tpm_atmel_priv *priv = dev_get_drvdata(&chip->dev);
> +	struct tpm_atmel_priv *priv;
>  
>  	if (chip) {
> +		priv = dev_get_drvdata(&chip->dev);
>  		tpm_chip_unregister(chip);
>  		if (priv->have_region)
>  			atmel_release_region(priv->base, priv->region_size);
> -- 
> 2.5.0
>