Re: [PATCH] tpm: set TPM_CHIP_FLAG_SUSPENDED early

[Jerry Snitselaar]

On Wed, Oct 30, 2024 at 12:36:47AM +0200, Jarkko Sakkinen wrote:
> Setting TPM_CHIP_FLAG_SUSPENDED in the end of tpm_pm_suspend() can be racy
> according to the bug report, as this leaves window for tpm_hwrng_read() to
> be called while the operation is in progress. Move setting of the flag
> into the beginning.
> 
> Cc: stable@xxxxxxxxxxxxxxx # v6.4+
> Fixes: 99d464506255 ("tpm: Prevent hwrng from activating during resume")
> Reported-by: Mike Seo <mikeseohyungjin@xxxxxxxxx>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219383
> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> ---
>  drivers/char/tpm/tpm-interface.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 8134f002b121..3f96bc8b95df 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -370,6 +370,8 @@ int tpm_pm_suspend(struct device *dev)
>  	if (!chip)
>  		return -ENODEV;
>  
> +	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
> +
>  	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
>  		goto suspended;
>  
> @@ -390,8 +392,6 @@ int tpm_pm_suspend(struct device *dev)
>  	}
>  
>  suspended:
> -	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
> -
>  	if (rc)
>  		dev_err(dev, "Ignoring error %d while suspending\n", rc);
>  	return 0;
> -- 
> 2.47.0
> 

Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>