Commit ddaf098e authored May 16, 2023 by Greg Kroah-Hartman

driver core: class: properly reference count class_dev_iter()

When class_dev_iter is initialized, the reference count for the subsys
private structure is incremented, but never decremented, causing a
memory leak over time. To resolve this, save off a pointer to the
internal structure into the class_dev_iter structure and then when the
iterator is finished, drop the reference count.

Reported-and-tested-by: <syzbot+e7afd76ad060fa0d2605@syzkaller.appspotmail.com>
Fixes: 7b884b7f ("driver core: class.c: convert to only use class_to_subsys")
Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Link: https://lore.kernel.org/r/2023051610-stove-condense-9a77@gregkh

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 1e94be78

drivers/base/class.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -320,6 +320,7 @@ void class_dev_iter_init(struct class_dev_iter iter, const struct class class,
		start_knode = &start->p->knode_class;
		klist_iter_init_node(&sp->klist_devices, &iter->ki, start_knode);
		iter->type = type;
		iter->sp = sp;
		}
		EXPORT_SYMBOL_GPL(class_dev_iter_init);

		@@ -361,6 +362,7 @@ EXPORT_SYMBOL_GPL(class_dev_iter_next);
		void class_dev_iter_exit(struct class_dev_iter *iter)
		{
		klist_iter_exit(&iter->ki);
		subsys_put(iter->sp);
		}
		EXPORT_SYMBOL_GPL(class_dev_iter_exit);

+1 −0

Original line number	Diff line number	Diff line
		@@ -74,6 +74,7 @@ struct class {
		struct class_dev_iter {
		struct klist_iter ki;
		const struct device_type *type;
		struct subsys_private *sp;
		};

		int __must_check class_register(const struct class *class);