This is a note to let you know that I've just added the patch titled
rapidio: avoid data race between file operation callbacks and mport_cdev_add().
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rapidio-avoid-data-race-between-file-operation-callb.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 46a4919608554782bc9eba3913d8f22d05cf0a43
Author: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
Date: Thu Jun 4 16:51:21 2020 -0700
rapidio: avoid data race between file operation callbacks and mport_cdev_add().
[ 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@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Alexandre Bounine <alex.bou9@xxxxxxxxx>
Cc: Matt Porter <mporter@xxxxxxxxxxxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Mike Marshall <hubcap@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Allison Randal <allison@xxxxxxxxxxx>
Cc: Pavel Andrianov <andrianov@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20200426112950.1803-1-madhuparnabhowmik10@xxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index 10af330153b5e..0b85a80ae7ef6 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -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;
