From 5dca69e26fe97f17d4a6cbd6872103c868577b14 Mon Sep 17 00:00:00 2001
From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Date: Wed, 23 Jun 2021 16:14:21 +0300
Subject: [PATCH] software node: Handle software node injection to an existing
device properly
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: b622b24519f5 ("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>
---
drivers/base/swnode.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index 3cc11b813f28c..d1f1a82401207 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -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;