From: Alberto Ruiz <[email protected]> If device_add() succeeds during CUSE initialization but a subsequent step (cdev_alloc() or cdev_add()) fails, the error path calls put_device() without first calling device_del(). This leaks the devtmpfs entry created by device_add(), leaving a stale /dev/<name> node that persists until reboot.
Since the cuse_conn is never linked into cuse_conntbl on the failure path, cuse_channel_release() sees cc->dev == NULL and skips device_unregister(), so no other code path cleans up the node. This has several consequences: - The device name is permanently poisoned: any subsequent attempt to create a CUSE device with the same name hits the stale sysfs entry, device_add() fails, and the new device is aborted. - The collision manifests as ENODEV returned to userspace with no dmesg diagnostic, making it very difficult to debug. - The failure is self-perpetuating: once a name is leaked, all future attempts with that name fail identically. Fix this by introducing an err_dev label that calls device_del() to undo device_add() before falling through to err_unlock. The existing err_unlock path from a device_add() failure correctly skips device_del() since the device was never added. Signed-off-by: Alberto Ruiz <[email protected]> --- fs/fuse/cuse.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index dfcb98a654d83bb34460a6e8c9e4b196dfdfdfbe..df9d50a9c0fab269102ec0e4b2d459ca2a390c59 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -391,7 +391,7 @@ static void cuse_process_init_reply(struct fuse_mount *fm, rc = -ENOMEM; cdev = cdev_alloc(); if (!cdev) - goto err_unlock; + goto err_dev; cdev->owner = THIS_MODULE; cdev->ops = &cuse_frontend_fops; @@ -417,6 +417,8 @@ static void cuse_process_init_reply(struct fuse_mount *fm, err_cdev: cdev_del(cdev); +err_dev: + device_del(dev); err_unlock: mutex_unlock(&cuse_lock); put_device(dev); -- 2.52.0
