[PATCH] tpm: avoid NULL pointer dereference in tpm_tis_send()

[Ilias Apalodimas]

Hi Heinrich, 

On Fri, Nov 26, 2021 at 11:54:52PM +0100, Heinrich Schuchardt wrote:
> You should not dereference a pointer before checking if it is NULL.
> 
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  drivers/tpm/tpm2_tis_core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tpm/tpm2_tis_core.c b/drivers/tpm/tpm2_tis_core.c
> index ec8c730fe9..0ff21a1ef7 100644
> --- a/drivers/tpm/tpm2_tis_core.c
> +++ b/drivers/tpm/tpm2_tis_core.c
> @@ -218,7 +218,7 @@ static int tpm_tis_ready(struct udevice *dev)
>  int tpm_tis_send(struct udevice *dev, const u8 *buf, size_t len)
>  {
>  	struct tpm_chip *chip = dev_get_priv(dev);
> -	struct tpm_tis_phy_ops *phy_ops = chip->phy_ops;
> +	struct tpm_tis_phy_ops *phy_ops;
>  	size_t burstcnt, wr_size, sent = 0;
>  	u8 data = TPM_STS_GO;
>  	u8 status;
> @@ -227,6 +227,8 @@ int tpm_tis_send(struct udevice *dev, const u8 *buf, size_t len)
>  	if (!chip)
>  		return -ENODEV;
>  
> +	phy_ops = chip->phy_ops;
> +

At this point I believe dev_get_priv() wont fail, since the device is
opened and running.  We can remove the if check though.

>  	ret = tpm_tis_request_locality(dev, 0);
>  	if (ret < 0)
>  		return -EBUSY;
> -- 
> 2.32.0
> 


Thanks!
/Ilias