fs: sysfs: Fix reference leak in sysfs_break_active_protection()

The sysfs_break_active_protection() routine has an obvious reference
leak in its error path.  If the call to kernfs_find_and_get() fails then
kn will be NULL, so the companion sysfs_unbreak_active_protection()
routine won't get called (and would only cause an access violation by
trying to dereference kn->parent if it was called).  As a result, the
reference to kobj acquired at the start of the function will never be
released.

Fix the leak by adding an explicit kobject_put() call when kn is NULL.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: 2afc9166f79b ("scsi: sysfs: Introduce sysfs_{un,}break_active_protection()")
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/8a4d3f0f-c5e3-4b70-a188-0ca433f9e6f9@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 6b7652fb805057b8a155a0c94a3746fcb72eb5c7..7cd64021d453de7494f974ee21b77bc9a0838a35 100644 (file)
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -463,6 +463,8 @@ struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
        kn = kernfs_find_and_get(kobj->sd, attr->name);
        if (kn)
                kernfs_break_active_protection(kn);
+       else
+               kobject_put(kobj);
        return kn;
 }
 EXPORT_SYMBOL_GPL(sysfs_break_active_protection);