Message ID | 20210630071451.15507-1-saubhik.mukherjee@gmail.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | char: tpm: vtpm_proxy: Fix race in init | expand |
On Wed, Jun 30, 2021 at 12:44:51PM +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> > --- Is this v2? What was changed? > 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 > > /Jarkko
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> --- drivers/char/tpm/tpm_vtpm_proxy.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-)