This is a note to let you know that I've just added the patch titled

kobject: Make sure the parent does not get released before its

to my driver-core git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git in the driver-core-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 4ef12f7198023c09ad6d25b652bd8748c965c7fa Mon Sep 17 00:00:00 2001

From: Heikki Krogerus heikki.krogerus@linux.intel.com Date: Wed, 13 May 2020 18:18:40 +0300 Subject: kobject: Make sure the parent does not get released before its children

In the function kobject_cleanup(), kobject_del(kobj) is called before the kobj->release(). That makes it possible to release the parent of the kobject before the kobject itself.

To fix that, adding function __kboject_del() that does everything that kobject_del() does except release the parent reference. kobject_cleanup() then calls __kobject_del() instead of kobject_del(), and separately decrements the reference count of the parent kobject after kobj->release() has been called.

Reported-by: Naresh Kamboju naresh.kamboju@linaro.org Reported-by: kernel test robot rong.a.chen@intel.com Fixes: 7589238a8cf3 ("Revert "software node: Simplify software_node_release() function"") Suggested-by: "Rafael J. Wysocki" rafael@kernel.org Signed-off-by: Heikki Krogerus heikki.krogerus@linux.intel.com Reviewed-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Reviewed-by: Brendan Higgins brendanhiggins@google.com Tested-by: Brendan Higgins brendanhiggins@google.com Acked-by: Randy Dunlap rdunlap@infradead.org Link: https://lore.kernel.org/r/20200513151840.36400-1-heikki.krogerus@linux.intel... Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/kobject.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/lib/kobject.c b/lib/kobject.c index 83198cb37d8d..2bd631460e18 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -599,14 +599,7 @@ int kobject_move(struct kobject *kobj, struct kobject *new_parent) } EXPORT_SYMBOL_GPL(kobject_move);

-/** - * kobject_del() - Unlink kobject from hierarchy. - * @kobj: object. - * - * This is the function that should be called to delete an object - * successfully added via kobject_add(). - */ -void kobject_del(struct kobject *kobj) +static void __kobject_del(struct kobject *kobj) { struct kernfs_node *sd; const struct kobj_type *ktype; @@ -625,9 +618,23 @@ void kobject_del(struct kobject *kobj)

kobj->state_in_sysfs = 0; kobj_kset_leave(kobj); - kobject_put(kobj->parent); kobj->parent = NULL; } + +/** + * kobject_del() - Unlink kobject from hierarchy. + * @kobj: object. + * + * This is the function that should be called to delete an object + * successfully added via kobject_add(). + */ +void kobject_del(struct kobject *kobj) +{ + struct kobject *parent = kobj->parent; + + __kobject_del(kobj); + kobject_put(parent); +} EXPORT_SYMBOL(kobject_del);

/** @@ -663,6 +670,7 @@ EXPORT_SYMBOL(kobject_get_unless_zero); */ static void kobject_cleanup(struct kobject *kobj) { + struct kobject *parent = kobj->parent; struct kobj_type *t = get_ktype(kobj); const char *name = kobj->name;

@@ -684,7 +692,7 @@ static void kobject_cleanup(struct kobject *kobj) if (kobj->state_in_sysfs) { pr_debug("kobject: '%s' (%p): auto cleanup kobject_del\n", kobject_name(kobj), kobj); - kobject_del(kobj); + __kobject_del(kobj); }

if (t && t->release) { @@ -698,6 +706,8 @@ static void kobject_cleanup(struct kobject *kobj) pr_debug("kobject: '%s': free name\n", name); kfree_const(name); } + + kobject_put(parent); }

#ifdef CONFIG_DEBUG_KOBJECT_RELEASE