[PATCH 5.11 084/210] driver core: Fix locking bug in deferred_probe_timeout_work_func()

Greg Kroah-Hartman
2021-04-12T09:31:07Z

From: Saravana Kannan <saravanak@google.com>

commit eed6e41813deb9ee622cd9242341f21430d7789f upstream.

list_for_each_entry_safe() is only useful if we are deleting nodes in a
linked list within the loop. It doesn't protect against other threads
adding/deleting nodes to the list in parallel. We need to grab
deferred_probe_mutex when traversing the deferred_probe_pending_list.

Cc: stable@vger.kernel.org
Fixes: 25b4e70dcce9 ("driver core: allow stopping deferred probe after init")
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20210402040342.2944858-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/dd.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -292,14 +292,16 @@ int driver_deferred_probe_check_state(st

static void deferred_probe_timeout_work_func(struct work_struct *work)
{
- struct device_private *private, *p;
+ struct device_private *p;

driver_deferred_probe_timeout = 0;
driver_deferred_probe_trigger();
flush_work(&deferred_probe_work);

- list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
- dev_info(private->device, "deferred probe pending\n");
+ mutex_lock(&deferred_probe_mutex);
+ list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
+ dev_info(p->device, "deferred probe pending\n");
+ mutex_unlock(&deferred_probe_mutex);
wake_up_all(&probe_timeout_waitqueue);
}
static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);