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SubjectRe: [PATCH] char: tpm: vtpm_proxy: Fix race in init
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

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