[PATCH 04/12] thunderbolt: Keep the domain reference while processing hotplug

[Mika Westerberg <mika.westerberg@linux.intel.com>]

We process hotplug events in a workqueue that may run after the domain
has been removed by tb_domain_remove(). For example if user unloads the
driver while at the same time plugging  a device router we may have
scheduled tb_handle_hotplug() to run. Avoid possible UAF in this case by
taking the domain reference before scheduling the hotplug handler in
tb_queue_hotplug().

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/tb.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index c69c323e6952..34b7d18cce56 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -98,7 +98,7 @@ static void tb_queue_hotplug(struct tb *tb, u64 route, u8 port, bool unplug)
 	if (!ev)
 		return;
 
-	ev->tb = tb;
+	ev->tb = tb_domain_get(tb);
 	ev->route = route;
 	ev->port = port;
 	ev->unplug = unplug;
@@ -2527,6 +2527,9 @@ static void tb_handle_hotplug(struct work_struct *work)
 	pm_runtime_mark_last_busy(&tb->dev);
 	pm_runtime_put_autosuspend(&tb->dev);
 
+	/* Undo the refcount increased in tb_queue_hotplug() */
+	tb_domain_put(tb);
+
 	kfree(ev);
 }
 
-- 
2.50.1