Messages in this thread Patch in this message | | | From | madhuparnabhowmik10@gmail ... | Subject | [PATCH] rapidio: Avoid data race between file operation callbacks and mport_cdev_add(). | Date | Sun, 26 Apr 2020 16:59:50 +0530 |
| |
From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Fields of md(mport_dev) are set after cdev_device_add(). However, the file operation callbacks can be called after cdev_device_add() and therefore accesses to fields of md in the callbacks can race with the rest of the mport_cdev_add() function.
One such example is INIT_LIST_HEAD(&md->portwrites) in mport_cdev_add(), the list is initialised after cdev_device_add(). This can race with list_add_tail(&pw_filter->md_node,&md->portwrites) in rio_mport_add_pw_filter() which is called by unlocked_ioctl.
To avoid such data races use cdev_device_add() after initializing md.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> --- drivers/rapidio/devices/rio_mport_cdev.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c index 8155f59ece38..40296378e5ee 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -2379,13 +2379,6 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport) cdev_init(&md->cdev, &mport_fops); md->cdev.owner = THIS_MODULE; - ret = cdev_device_add(&md->cdev, &md->dev); - if (ret) { - rmcd_error("Failed to register mport %d (err=%d)", - mport->id, ret); - goto err_cdev; - } - INIT_LIST_HEAD(&md->doorbells); spin_lock_init(&md->db_lock); INIT_LIST_HEAD(&md->portwrites); @@ -2405,6 +2398,13 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport) #else md->properties.transfer_mode |= RIO_TRANSFER_MODE_TRANSFER; #endif + + ret = cdev_device_add(&md->cdev, &md->dev); + if (ret) { + rmcd_error("Failed to register mport %d (err=%d)", + mport->id, ret); + goto err_cdev; + } ret = rio_query_mport(mport, &attr); if (!ret) { md->properties.flags = attr.flags; -- 2.17.1
| |