[PATCH 4.18 044/350] nvme: remove ns sibling before clearing path

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Keith Busch <keith.busch@xxxxxxxxx>

[ Upstream commit 48f78be3326052a7718678ff9a78d6d884a50323 ]

The code had been clearing a namespace being deleted as the current
path while that namespace was still in the path siblings list. It is
possible a new IO could set that namespace back to the current path
since it appeared to be an eligable path to select, which may result in
a use-after-free error.

This patch ensures a namespace being removed is not eligable to be reset
as a current path prior to clearing it as the current path.

Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/nvme/host/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3119,8 +3119,8 @@ static void nvme_ns_remove(struct nvme_n
 	}
 
 	mutex_lock(&ns->ctrl->subsys->lock);
-	nvme_mpath_clear_current_path(ns);
 	list_del_rcu(&ns->siblings);
+	nvme_mpath_clear_current_path(ns);
 	mutex_unlock(&ns->ctrl->subsys->lock);
 
 	down_write(&ns->ctrl->namespaces_rwsem);