linux-kernel - [PATCH AUTOSEL 4.18 03/33] nvme: remove ns sibling before clearing path

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Date:   Tue, 30 Oct 2018 09:26:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Keith Busch <keith.busch@...el.com>,
        Christoph Hellwig <hch@....de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.18 03/33] nvme: remove ns sibling before clearing path

From: Keith Busch <keith.busch@...el.com>

[ 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@...el.com>
Reviewed-by: Sagi Grimberg <sagi@...mberg.me>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvme/host/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index bf65501e6ed6..f1f375fb362b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3119,8 +3119,8 @@ static void nvme_ns_remove(struct nvme_ns *ns)
 	}
 
 	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);
-- 
2.17.1