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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Maurizio Lombardi <mlombard@redhat.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        Christoph Hellwig <hch@lst.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.12 212/292] nvme-tcp: cant set sk_user_data without write_lock
Date:   Mon, 19 Jul 2021 16:54:34 +0200
Message-Id: <20210719144949.968781897@linuxfoundation.org>
In-Reply-To: <20210719144942.514164272@linuxfoundation.org>
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From: Maurizio Lombardi <mlombard@redhat.com>

[ Upstream commit 0755d3be2d9bb6ea38598ccd30d6bbaa1a5c3a50 ]

The sk_user_data pointer is supposed to be modified only while
holding the write_lock "sk_callback_lock", otherwise
we could race with other threads and crash the kernel.

we can't take the write_lock in nvmet_tcp_state_change()
because it would cause a deadlock, but the release_work queue
will set the pointer to NULL later so we can simply remove
the assignment.

Fixes: b5332a9f3f3d ("nvmet-tcp: fix incorrect locking in state_change sk callback")

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/nvme/target/tcp.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 4df4f37e6b89..dedcb7aaf0d8 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -1467,7 +1467,6 @@ static void nvmet_tcp_state_change(struct sock *sk)
 	case TCP_CLOSE_WAIT:
 	case TCP_CLOSE:
 		/* FALLTHRU */
-		sk->sk_user_data = NULL;
 		nvmet_tcp_schedule_release_queue(queue);
 		break;
 	default:
-- 
2.30.2