From: Madhuparna Bhowmik madhuparnabhowmik10@gmail.com
[ Upstream commit e1c3cdb26ab881b77486dc50370356a349077c74 ]
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 Signed-off-by: Andrew Morton akpm@linux-foundation.org Acked-by: Alexandre Bounine alex.bou9@gmail.com Cc: Matt Porter mporter@kernel.crashing.org Cc: Dan Carpenter dan.carpenter@oracle.com Cc: Mike Marshall hubcap@omnibond.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ira Weiny ira.weiny@intel.com Cc: Allison Randal allison@lohutok.net Cc: Pavel Andrianov andrianov@ispras.ru Link: http://lkml.kernel.org/r/20200426112950.1803-1-madhuparnabhowmik10@gmail.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 5940780648e0f..f36a8a5261a13 100644 --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -2385,13 +2385,6 @@ 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); @@ -2411,6 +2404,13 @@ 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;