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Commit 3abef3b3 authored by Alex Elder's avatar Alex Elder
Browse files

rbd: fix cleanup in rbd_add() 



Bjorn Helgaas pointed out that a recent commit introduced a
use-after-free condition in an error path for rbd_add().
He correctly stated:

    I think b536f69a "rbd: set up devices only for mapped images"
    introduced a use-after-free error in rbd_add():
	...
    If rbd_dev_device_setup() returns an error, we call
    rbd_dev_image_release(), which ultimately kfrees rbd_dev.
    Then we call rbd_dev_destroy(), which references fields in
    the already-freed rbd_dev struct before kfreeing it again.

The simple fix is to return the error code after the call to
rbd_dev_image_release().

Closer examination revealed that there's no need to clean up
rbd_opts in that function, so fix that too.

Update some other comments that have also become out of date.

Reported-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 7262cfca

drivers/block/rbd.c

+14 −9
Original line number Diff line number Diff line
@@ -4700,8 +4700,10 @@ out: 
	return ret;

}



/* Undo whatever state changes are made by v1 or v2 image probe */



/*

 * Undo whatever state changes are made by v1 or v2 header info

 * call.

 */

static void rbd_dev_unprobe(struct rbd_device *rbd_dev)

{

	struct rbd_image_header	*header;
@@ -4905,9 +4907,10 @@ static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping) 
	int tmp;



	/*

	 * Get the id from the image id object.  If it's not a

	 * format 2 image, we'll get ENOENT back, and we'll assume

	 * it's a format 1 image.

	 * Get the id from the image id object.  Unless there's an

	 * error, rbd_dev->spec->image_id will be filled in with

	 * a dynamically-allocated string, and rbd_dev->image_format

	 * will be set to either 1 or 2.

	 */

	ret = rbd_dev_image_id(rbd_dev);

	if (ret)
@@ -5029,16 +5032,18 @@ static ssize_t rbd_add(struct bus_type *bus, 
	rbd_dev->mapping.read_only = read_only;



	rc = rbd_dev_device_setup(rbd_dev);

	if (!rc)

	if (rc) {

		rbd_dev_image_release(rbd_dev);

		goto err_out_module;

	}



	return count;



	rbd_dev_image_release(rbd_dev);

err_out_rbd_dev:

	rbd_dev_destroy(rbd_dev);

err_out_client:

	rbd_put_client(rbdc);

err_out_args:

	kfree(rbd_opts);

	rbd_spec_put(spec);

err_out_module:

	module_put(THIS_MODULE);