The patch titled
Subject: rapidio: avoid data race between file operation callbacks and mport_cdev_add().
has been added to the -mm tree. Its filename is
rapidio-avoid-data-race-between-file-operation-callbacks-and-mport_cdev_add.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rapidio-avoid-data-race-between-file-operation-callbacks-and-mport_cdev_add.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/rapidio-avoid-data-race-between-file-operation-callbacks-and-mport_cdev_add.patch
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------------------------------------------------------
From: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
Subject: 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).
Link: http://lkml.kernel.org/r/20200426112950.1803-1-madhuparnabhowmik10@xxxxxxxxx
Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rapidio/devices/rio_mport_cdev.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- a/drivers/rapidio/devices/rio_mport_cdev.c~rapidio-avoid-data-race-between-file-operation-callbacks-and-mport_cdev_add
+++ a/drivers/rapidio/devices/rio_mport_cdev.c
@@ -2379,13 +2379,6 @@ static struct mport_dev *mport_cdev_add(
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(
#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;
_
Patches currently in -mm which might be from madhuparnabhowmik10@xxxxxxxxx are
rapidio-avoid-data-race-between-file-operation-callbacks-and-mport_cdev_add.patch
