From ed01e50acdd3e4a640cf9ebd28a7e810c3ceca97 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Fri, 17 Mar 2017 12:48:09 -0600 Subject: device-dax: fix cdev leak 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: Reported-by: Jason Gunthorpe Signed-off-by: Dan Williams Signed-off-by: Logan Gunthorpe Reviewed-by: Johannes Thumshirn Signed-off-by: Greg Kroah-Hartman --- drivers/dax/dax.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c index 8d9829ff2a78..a5ed59a5a968 100644 --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -675,13 +675,10 @@ 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 @@ -693,6 +690,15 @@ 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); } @@ -769,6 +775,7 @@ 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); } -- cgit v1.2.3 From 92a3fa075d3d2716b9c662814540f1d660cbf2f5 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Fri, 17 Mar 2017 12:48:10 -0600 Subject: device-dax: utilize new cdev_device_add helper function Replace the open coded registration of the cdev and dev with the new device_add_cdev() helper. The helper replaces a common pattern by taking the proper reference against the parent device and adding both the cdev and the device. Signed-off-by: Logan Gunthorpe Reviewed-by: Dan Williams Reviewed-by: Johannes Thumshirn Signed-off-by: Greg Kroah-Hartman --- drivers/dax/dax.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c index a5ed59a5a968..e5f85550dc25 100644 --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -677,8 +677,6 @@ static void dax_dev_release(struct device *dev) static void kill_dax_dev(struct dax_dev *dax_dev) { - struct cdev *cdev = &dax_dev->cdev; - /* * Note, rcu is not protecting the liveness of dax_dev, rcu is * ensuring that any fault handlers that might have seen @@ -689,7 +687,6 @@ static void kill_dax_dev(struct dax_dev *dax_dev) dax_dev->alive = false; synchronize_rcu(); unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1); - cdev_del(cdev); } static void unregister_dax_dev(void *dev) @@ -699,7 +696,8 @@ static void unregister_dax_dev(void *dev) dev_dbg(dev, "%s\n", __func__); kill_dax_dev(dax_dev); - device_unregister(dev); + cdev_device_del(&dax_dev->cdev, dev); + put_device(dev); } struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region, @@ -750,18 +748,13 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region, goto err_inode; } - /* device_initialize() so cdev can reference kobj parent */ + /* from here on we're committed to teardown via dax_dev_release() */ device_initialize(dev); cdev = &dax_dev->cdev; cdev_init(cdev, &dax_fops); cdev->owner = parent->driver->owner; - cdev->kobj.parent = &dev->kobj; - rc = cdev_add(&dax_dev->cdev, dev_t, 1); - if (rc) - goto err_cdev; - /* from here on we're committed to teardown via dax_dev_release() */ dax_dev->num_resources = count; dax_dev->alive = true; dax_dev->region = dax_region; @@ -773,7 +766,8 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region, dev->groups = dax_attribute_groups; dev->release = dax_dev_release; dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id); - rc = device_add(dev); + + rc = cdev_device_add(cdev, dev); if (rc) { kill_dax_dev(dax_dev); put_device(dev); @@ -786,8 +780,6 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region, return dax_dev; - err_cdev: - iput(dax_dev->inode); err_inode: ida_simple_remove(&dax_minor_ida, minor); err_minor: -- cgit v1.2.3