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From: Jarkko Sakkinen <jarkko@kernel.org>
To: Saubhik Mukherjee <saubhik.mukherjee@gmail.com>
Cc: peterhuewe@gmx.de, jgg@ziepe.ca, linux-integrity@vger.kernel.org,
	linux-kernel@vger.kernel.org, ldv-project@linuxtesting.org,
	andrianov@ispras.ru
Subject: Re: [PATCH] char: tpm: vtpm_proxy: Fix race in init
Date: Tue, 29 Jun 2021 20:27:00 +0300	[thread overview]
Message-ID: <20210629172700.yxqnedbayumo5f24@kernel.org> (raw)
In-Reply-To: <20210623132226.140341-1-saubhik.mukherjee@gmail.com>

On Wed, Jun 23, 2021 at 06:52:26PM +0530, Saubhik Mukherjee wrote:
> vtpm_module_init calls vtpmx_init which calls misc_register. The file
> operations callbacks are registered. So, vtpmx_fops_ioctl can execute in
> parallel with rest of vtpm_module_init. vtpmx_fops_ioctl calls
> vtpmx_ioc_new_dev, which calls vtpm_proxy_create_device, which calls
> vtpm_proxy_work_start, which could read uninitialized workqueue.
> 
> To avoid this, create workqueue before vtpmx init.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Saubhik Mukherjee <saubhik.mukherjee@gmail.com>
> ---
>  drivers/char/tpm/tpm_vtpm_proxy.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
> index 91c772e38bb5..225dfa026a8f 100644
> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
> @@ -697,23 +697,22 @@ static int __init vtpm_module_init(void)
>  {
>  	int rc;
>  
> -	rc = vtpmx_init();
> -	if (rc) {
> -		pr_err("couldn't create vtpmx device\n");
> -		return rc;
> -	}
> -
>  	workqueue = create_workqueue("tpm-vtpm");
>  	if (!workqueue) {
>  		pr_err("couldn't create workqueue\n");
> -		rc = -ENOMEM;
> -		goto err_vtpmx_cleanup;
> +		return -ENOMEM;
> +	}
> +
> +	rc = vtpmx_init();
> +	if (rc) {
> +		pr_err("couldn't create vtpmx device\n");
> +		goto err_destroy_workqueue;
>  	}
>  
>  	return 0;
>  
> -err_vtpmx_cleanup:
> -	vtpmx_cleanup();
> +err_destroy_workqueue:
> +	destroy_workqueue(workqueue);
>  
>  	return rc;
>  }
> -- 
> 2.30.2
> 
> 

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

/Jarkko

  reply	other threads:[~2021-06-29 17:27 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-23 13:22 Saubhik Mukherjee
2021-06-29 17:27 ` Jarkko Sakkinen [this message]
2021-06-29 21:05   ` Jarkko Sakkinen
2021-06-30  7:14     ` Saubhik Mukherjee
2021-07-02  6:37       ` Jarkko Sakkinen
2021-06-30  7:24     ` Saubhik Mukherjee
2021-07-02  6:38       ` Jarkko Sakkinen

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