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Commit 30783587 authored by David Herrmann's avatar David Herrmann Committed by Miklos Szeredi
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cuse: do not register multiple devices with identical names 



Sysfs doesn't allow two devices with the same name, but we register a
sysfs entry for each cuse device without checking for name collisions.
This extends the registration to first check whether the name was already
registered.

To avoid race-conditions between the name-check and linking the device, we
need to protect the whole registration with a mutex.

Signed-off-by: default avatarDavid Herrmann <dh.herrmann@googlemail.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 8ce03fd7

fs/fuse/cuse.c

+15 −6
Original line number Diff line number Diff line
@@ -304,14 +304,14 @@ static void cuse_gendev_release(struct device *dev) 
 */

static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req)

{

	struct cuse_conn *cc = fc_to_cc(fc);

	struct cuse_conn *cc = fc_to_cc(fc), *pos;

	struct cuse_init_out *arg = req->out.args[0].value;

	struct page *page = req->pages[0];

	struct cuse_devinfo devinfo = { };

	struct device *dev;

	struct cdev *cdev;

	dev_t devt;

	int rc;

	int rc, i;



	if (req->out.h.error ||

	    arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) {
@@ -355,15 +355,24 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 
	dev_set_drvdata(dev, cc);

	dev_set_name(dev, "%s", devinfo.name);



	mutex_lock(&cuse_lock);



	/* make sure the device-name is unique */

	for (i = 0; i < CUSE_CONNTBL_LEN; ++i) {

		list_for_each_entry(pos, &cuse_conntbl[i], list)

			if (!strcmp(dev_name(pos->dev), dev_name(dev)))

				goto err_unlock;

	}



	rc = device_add(dev);

	if (rc)

		goto err_device;

		goto err_unlock;



	/* register cdev */

	rc = -ENOMEM;

	cdev = cdev_alloc();

	if (!cdev)

		goto err_device;

		goto err_unlock;



	cdev->owner = THIS_MODULE;

	cdev->ops = &cuse_frontend_fops;
@@ -376,7 +385,6 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 
	cc->cdev = cdev;



	/* make the device available */

	mutex_lock(&cuse_lock);

	list_add(&cc->list, cuse_conntbl_head(devt));

	mutex_unlock(&cuse_lock);
@@ -390,7 +398,8 @@ static void cuse_process_init_reply(struct fuse_conn *fc, struct fuse_req *req) 


err_cdev:

	cdev_del(cdev);

err_device:

err_unlock:

	mutex_unlock(&cuse_lock);

	put_device(dev);

err_region:

	unregister_chrdev_region(devt, 1);