linux-kernel - [PATCH 5.4 160/355] nvmet: fix use-after-free when a port is removed

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Message-Id: <20211115165318.958980422@linuxfoundation.org>
Date:   Mon, 15 Nov 2021 18:01:24 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Israel Rukshin <israelr@...dia.com>,
        Max Gurtovoy <mgurtovoy@...dia.com>,
        Christoph Hellwig <hch@....de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 160/355] nvmet: fix use-after-free when a port is removed

From: Israel Rukshin <israelr@...dia.com>

[ Upstream commit e3e19dcc4c416d65f99f13d55be2b787f8d0050e ]

When a port is removed through configfs, any connected controllers
are starting teardown flow asynchronously and can still send commands.
This causes a use-after-free bug for any command that dereferences
req->port (like in nvmet_parse_io_cmd).

To fix this, wait for all the teardown scheduled works to complete
(like release_work at rdma/tcp drivers). This ensures there are no
active controllers when the port is eventually removed.

Signed-off-by: Israel Rukshin <israelr@...dia.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@...dia.com>
Signed-off-by: Christoph Hellwig <hch@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/nvme/target/configfs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 98613a45bd3b4..baf8a3e4ed12a 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1148,6 +1148,8 @@ static void nvmet_port_release(struct config_item *item)
 {
 	struct nvmet_port *port = to_nvmet_port(item);
 
+	/* Let inflight controllers teardown complete */
+	flush_scheduled_work();
 	list_del(&port->global_entry);
 
 	kfree(port->ana_state);
-- 
2.33.0