| Message ID | 20210708095259.27915-1-saubhik.mukherjee@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] char: tpm: vtpm_proxy: Fix race in init | expand |
On Thu, Jul 08, 2021 at 03:22:59PM +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). > > Fixes: 6f99612e2500 ("tpm: Proxy driver for supporting multiple emulated TPMs") > Signed-off-by: Saubhik Mukherjee <saubhik.mukherjee@gmail.com> > --- > > Changes since v1 ([0]): > - Add Fixes tag to commit message, as requested by Jarkko in [1]. > > [0]: https://lkml.org/lkml/2021/6/23/572 > [1]: https://lkml.org/lkml/2021/6/29/695 > > 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 > > Thanks, I applied this. Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> /Jarkko
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@gmail.com> Tested-by: Stefan Berger <stefanb@linux.ibm.com>
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; }
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@gmail.com> --- Changes since v1 ([0]): - Add Fixes tag to commit message, as requested by Jarkko in [1]. [0]: https://lkml.org/lkml/2021/6/23/572 [1]: https://lkml.org/lkml/2021/6/29/695 drivers/char/tpm/tpm_vtpm_proxy.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-)