[PATCH] driver core: check 'start' argument in bus iterators

[Hannes Reinecke <hare@suse.de>]

bus_for_each_dev() and bus_find_device() both take a 'start'
argument to start the iteration at a specific list entry.
However, this list entry might already been detached by
the time these functions are called.
So we need to check if the arguments are still valid.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Cc: Greg Kroah-Hartmann <gregkh@linuxfoundation.org>
Cc: Kay Sievers <ksievers@vrfy.org>
Cc: Stable Kernel <stable@kernel.org>

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 26a06b8..264e498 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -297,6 +297,9 @@ int bus_for_each_dev(struct bus_type *bus, struct device *start,
 	if (!bus)
 		return -EINVAL;
 
+	if (start && !klist_node_attached(&start->p->knode_bus))
+		return -ENODEV;
+
 	klist_iter_init_node(&bus->p->klist_devices, &i,
 			     (start ? &start->p->knode_bus : NULL));
 	while ((dev = next_device(&i)) && !error)
@@ -331,6 +334,9 @@ struct device *bus_find_device(struct bus_type *bus,
 	if (!bus)
 		return NULL;
 
+	if (start && !klist_node_attached(&start->p->knode_bus))
+		return NULL;
+
 	klist_iter_init_node(&bus->p->klist_devices, &i,
 			     (start ? &start->p->knode_bus : NULL));
 	while ((dev = next_device(&i)))