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rapidio: avoid data race between file operation callbacks and mport_cdev_add(). 

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>
This commit is contained in:
Madhuparna Bhowmik 2020-06-04 16:51:21 -07:00 committed by Linus Torvalds
parent 762a3af6fa
commit e1c3cdb26a
1 changed files with 7 additions and 7 deletions
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14
drivers/rapidio/devices/rio_mport_cdev.c
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@ -2384,13 +2384,6 @@ 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);
@ -2410,6 +2403,13 @@ 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;