xen/xenbus: reference count registered modules (196748a2) · Commits · 戴 / test

To prevent a PV driver module being removed whilst attached to its other end, and hence xenbus calling into potentially invalid text, take a reference on the module before calling the probe() method (dropping it if unsuccessful) and drop the reference after returning from the remove() method. Suggested-by:

Jan Beulich <jbeulich@suse.com> Signed-off-by:

Paul Durrant <pdurrant@amazon.com> Reviewed-by:

Jan Beulich <jbeulich@suse.com> Reviewed-by:

Juergen Gross <jgross@suse.com> Signed-off-by:

Juergen Gross <jgross@suse.com>

drivers/xen/xenbus/xenbus_probe.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -232,9 +232,16 @@ int xenbus_dev_probe(struct device *_dev)
		return err;
		}

		if (!try_module_get(drv->driver.owner)) {
		dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n",
		drv->driver.name);
		err = -ESRCH;
		goto fail;
		}

		err = drv->probe(dev, id);
		if (err)
		goto fail;
		goto fail_put;

		err = watch_otherend(dev);
		if (err) {
		@@ -244,6 +251,8 @@ int xenbus_dev_probe(struct device *_dev)
		}

		return 0;
		fail_put:
		module_put(drv->driver.owner);
		fail:
		xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
		xenbus_switch_state(dev, XenbusStateClosed);
		@@ -263,6 +272,8 @@ int xenbus_dev_remove(struct device *_dev)
		if (drv->remove)
		drv->remove(dev);

		module_put(drv->driver.owner);

		free_otherend_details(dev);

		xenbus_switch_state(dev, XenbusStateClosed);

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