[PATCH v2 02/16] device-dax: fix cdev leak
From: Logan Gunthorpe <hidden>
Date: 2017-02-26 06:38:03
Also in:
linux-fsdevel, linux-gpio, linux-rdma, linux-rtc, linux-scsi, nvdimm
Subsystem:
device direct access (dax), the rest · Maintainers:
Dan Williams, Vishal Verma, Dave Jiang, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2017-02-26 · Re: [PATCH v2 02/16] device-dax: fix cdev leak · Dan Williams <hidden>
From: Dan Williams <redacted>
If device_add() fails, cleanup the cdev. Otherwise, we leak a kobj_map()
with a stale device number.
As Jason points out, there is a small possibility that userspace has
opened and mapped the device in the time between cdev_add() and the
device_add() failure. We need a new kill_dax_dev() helper to invalidate
any established mappings.
Fixes: ba09c01d2fa8 ("dax: convert to the cdev api")
Cc: <redacted>
Cc: Logan Gunthorpe <logang-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
Reported-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Signed-off-by: Dan Williams <redacted>
---
drivers/dax/dax.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index ed758b7..b62a52f 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c@@ -630,13 +630,10 @@ static void dax_dev_release(struct device *dev) kfree(dax_dev); } -static void unregister_dax_dev(void *dev) +static void kill_dax_dev(struct dax_dev *dax_dev) { - struct dax_dev *dax_dev = to_dax_dev(dev); struct cdev *cdev = &dax_dev->cdev; - dev_dbg(dev, "%s\n", __func__); - /* * Note, rcu is not protecting the liveness of dax_dev, rcu is * ensuring that any fault handlers that might have seen
@@ -648,6 +645,15 @@ static void unregister_dax_dev(void *dev) synchronize_rcu(); unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1); cdev_del(cdev); +} + +static void unregister_dax_dev(void *dev) +{ + struct dax_dev *dax_dev = to_dax_dev(dev); + + dev_dbg(dev, "%s\n", __func__); + + kill_dax_dev(dax_dev); device_unregister(dev); }
@@ -724,6 +730,7 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region, dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id); rc = device_add(dev); if (rc) { + kill_dax_dev(dax_dev); put_device(dev); return ERR_PTR(rc); }
--
2.1.4