linux-kernel - Re: [PATCH v2] tpm: Fix the driver cleanup code

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Date:   Fri, 22 Dec 2017 20:41:44 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Azhar Shaikh <azhar.shaikh@...el.com>
Cc:     jgg@...pe.ca, javierm@...hat.com, peterhuewe@....de,
        linux-security-module@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tpm: Fix the driver cleanup code

On Thu, Dec 21, 2017 at 03:13:39PM -0800, Azhar Shaikh wrote:
> Commit 3c1701339284353c41 ("tpm: Keep CLKRUN enabled throughout
> the duration of transmit_cmd()") added code which accessed
> chip->ops, even after it was set to NULL in tpm_del_char_device(),
> called from tpm_chip_unregister() in error / driver exit paths.
> So fix this code.
> 
> Fixes: 3c1701339284353c41 ("tpm: Keep CLKRUN enabled throughout
> the duration of transmit_cmd()")
> 
> Suggested-by: Javier Martinez Canillas <javierm@...hat.com>
> Suggested-by: Jason Gunthorpe <jgg@...pe.ca>
> Signed-off-by: Azhar Shaikh <azhar.shaikh@...el.com>
> ---
> Changes in v2:
> - Remove TPM_CHIP_FLAG_DO_NOT_CLEAR_OPS flag, instead call
>   tpm_tis_clkrun_enable() directly in tpm_tis_remove()
> - Add comment to tpm_tis_clkrun_enable()
> 
>  drivers/char/tpm/tpm_tis.c      |  6 ------
>  drivers/char/tpm/tpm_tis_core.c | 29 +++++++++++++++++------------
>  2 files changed, 17 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> index d29add49b033..c847fc69a2fc 100644
> --- a/drivers/char/tpm/tpm_tis.c
> +++ b/drivers/char/tpm/tpm_tis.c
> @@ -275,9 +275,6 @@ static void tpm_tis_pnp_remove(struct pnp_dev *dev)
>  
>  	tpm_chip_unregister(chip);
>  	tpm_tis_remove(chip);
> -	if (is_bsw())
> -		iounmap(priv->ilb_base_addr);
> -
>  }
>  
>  static struct pnp_driver tis_pnp_driver = {
> @@ -329,9 +326,6 @@ static int tpm_tis_plat_remove(struct platform_device *pdev)
>  	tpm_chip_unregister(chip);
>  	tpm_tis_remove(chip);
>  
> -	if (is_bsw())
> -		iounmap(priv->ilb_base_addr);
> -
>  	return 0;
>  }
>  
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index c2227983ed88..519e4a78c8f8 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -37,6 +37,8 @@
>   */
>  #define TPM_POLL_SLEEP	1  /* msec */
>  
> +static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value);
> +
>  static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
>  					bool check_cancel, bool *canceled)
>  {
> @@ -716,8 +718,7 @@ void tpm_tis_remove(struct tpm_chip *chip)
>  	u32 interrupt;
>  	int rc;
>  
> -	if (chip->ops->clk_enable != NULL)
> -		chip->ops->clk_enable(chip, true);
> +	tpm_tis_clkrun_enable(chip, true);
>  
>  	rc = tpm_tis_read32(priv, reg, &interrupt);
>  	if (rc < 0)
> @@ -725,8 +726,10 @@ void tpm_tis_remove(struct tpm_chip *chip)
>  
>  	tpm_tis_write32(priv, reg, ~TPM_GLOBAL_INT_ENABLE & interrupt);
>  
> -	if (chip->ops->clk_enable != NULL)
> -		chip->ops->clk_enable(chip, false);
> +	tpm_tis_clkrun_enable(chip, false);
> +
> +	if (priv->ilb_base_addr)
> +		iounmap(priv->ilb_base_addr);
>  }
>  EXPORT_SYMBOL_GPL(tpm_tis_remove);
>  
> @@ -736,6 +739,9 @@ void tpm_tis_remove(struct tpm_chip *chip)
>   * @chip:	TPM chip to use
>   * @value:	1 - Disable CLKRUN protocol, so that clocks are free running
>   *		0 - Enable CLKRUN protocol
> + *
> + * Call this function directly in tpm_tis_remove() in error or driver removal
> + * path, since the chip->ops is set to NULL in tpm_chip_unregister().
>   */
>  static void tpm_tis_clkrun_enable(struct tpm_chip *chip, bool value)
>  {
> @@ -922,21 +928,20 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
>  	}
>  
>  	rc = tpm_chip_register(chip);
> -	if (rc && is_bsw())
> -		iounmap(priv->ilb_base_addr);
> +	if (rc)
> +		goto out_err;
>  
>  	if (chip->ops->clk_enable != NULL)
>  		chip->ops->clk_enable(chip, false);
>  
> -	return rc;
> -out_err:
> -	tpm_tis_remove(chip);
> -	if (is_bsw())
> -		iounmap(priv->ilb_base_addr);
> +	return 0;
>  
> -	if (chip->ops->clk_enable != NULL)
> +out_err:
> +	if ((chip->ops != NULL) && (chip->ops->clk_enable != NULL))
>  		chip->ops->clk_enable(chip, false);
>  
> +	tpm_tis_remove(chip);
> +
>  	return rc;
>  }
>  EXPORT_SYMBOL_GPL(tpm_tis_core_init);
> -- 
> 1.9.1
> 

Since the original commit is not in the mainline yet, you should rather
send an updated version of that commit.

/Jarkko