From: Heikki Krogerus heikki.krogerus@linux.intel.com
[ Upstream commit 5dca69e26fe97f17d4a6cbd6872103c868577b14 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 88310ac9ce90..62c536f9d925 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -1032,7 +1032,15 @@ 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; } @@ -1052,7 +1060,8 @@ 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); } @@ -1106,8 +1115,7 @@ 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;