From 2f13bd8f39af8f85561b90c7738612584c8b4d15 Mon Sep 17 00:00:00 2001 From: Heikki Krogerus Date: Wed, 23 Jun 2021 16:14:21 +0300 Subject: [PATCH] UPSTREAM: 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 Reviewed-by: Andy Shevchenko Signed-off-by: Heikki Krogerus Signed-off-by: Rafael J. Wysocki (cherry picked from commit 5dca69e26fe97f17d4a6cbd6872103c868577b14) Bug: 187129171 Signed-off-by: Connor O'Brien Change-Id: I1caca7eaaf76e9b6e48151cecf2219743690ba93 --- 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 254f31443132..c9867ced8011 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -893,7 +893,15 @@ 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; } @@ -913,7 +921,8 @@ 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); } @@ -930,8 +939,7 @@ 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;