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software node: Handle software node injection to an existing device properly

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The function software_node_notify() - the function that creates
and removes the symlinks between the node and the device - was
called unconditionally in device_add_software_node() and
device_remove_software_node(), but it needs to be called in
those functions only in the special case where the node is
added to a device that has already been registered.

This fixes NULL pointer dereference that happens if
device_remove_software_node() is used with device that was
never registered.

Fixes: b622b24519 ("software node: Allow node addition to already existing device")
Reported-and-tested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Heikki Krogerus 2021-06-23 16:14:21 +03:00 committed by Rafael J. Wysocki
parent 13311e7425
commit 5dca69e26f
1 changed files with 12 additions and 4 deletions
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16
drivers/base/swnode.c
View file

@ -1045,7 +1045,15 @@ int device_add_software_node(struct device *dev, const struct software_node *nod
}
set_secondary_fwnode(dev, &swnode->fwnode);
software_node_notify(dev, KOBJ_ADD);
/*
* If the device has been fully registered by the time this function is
* called, software_node_notify() must be called separately so that the
* symlinks get created and the reference count of the node is kept in
* balance.
*/
if (device_is_registered(dev))
software_node_notify(dev, KOBJ_ADD);
return 0;
}
@ -1065,7 +1073,8 @@ void device_remove_software_node(struct device *dev)
if (!swnode)
return;
software_node_notify(dev, KOBJ_REMOVE);
if (device_is_registered(dev))
software_node_notify(dev, KOBJ_REMOVE);
set_secondary_fwnode(dev, NULL);
kobject_put(&swnode->kobj);
}
@ -1119,8 +1128,7 @@ int software_node_notify(struct device *dev, unsigned long action)
switch (action) {
case KOBJ_ADD:
ret = sysfs_create_link_nowarn(&dev->kobj, &swnode->kobj,
"software_node");
ret = sysfs_create_link(&dev->kobj, &swnode->kobj, "software_node");
if (ret)
break;