linux-kernel - Re: [PATCH v2] char: tpm: vtpm

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Message-ID: <86011d11-522d-a686-b360-43d19366cab7@linux.ibm.com>
Date:   Fri, 9 Jul 2021 14:18:50 -0400
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Saubhik Mukherjee <saubhik.mukherjee@...il.com>, peterhuewe@....de,
        jarkko@...nel.org, jgg@...pe.ca
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org, andrianov@...ras.ru
Subject: Re: [PATCH v2] char: tpm: vtpm_proxy: Fix race in init


On 7/8/21 5:52 AM, 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).
>
> Fixes: 6f99612e2500 ("tpm: Proxy driver for supporting multiple emulated TPMs")
> Signed-off-by: Saubhik Mukherjee <saubhik.mukherjee@...il.com>

Tested-by: Stefan Berger <stefanb@...ux.ibm.com>