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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,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        Anna Schumaker <Anna.Schumaker@Netapp.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 050/260] SUNRPC: Fix potential memory corruption
Date:   Mon, 20 Sep 2021 18:41:08 +0200
Message-Id: <20210920163932.810824907@linuxfoundation.org>
In-Reply-To: <20210920163931.123590023@linuxfoundation.org>
References: <20210920163931.123590023@linuxfoundation.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit c2dc3e5fad13aca5d7bdf4bcb52b1a1d707c8555 ]

We really should not call rpc_wake_up_queued_task_set_status() with
xprt->snd_task as an argument unless we are certain that is actually an
rpc_task.

Fixes: 0445f92c5d53 ("SUNRPC: Fix disconnection races")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/sunrpc/xprt.h | 1 +
 net/sunrpc/xprt.c           | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index d7ef5b97174c..3c6c4b1dbf1a 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -419,6 +419,7 @@ void			xprt_unlock_connect(struct rpc_xprt *, void *);
 #define XPRT_CONGESTED		(9)
 #define XPRT_CWND_WAIT		(10)
 #define XPRT_WRITE_SPACE	(11)
+#define XPRT_SND_IS_COOKIE	(12)
 
 static inline void xprt_set_connected(struct rpc_xprt *xprt)
 {
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 639837b3a5d9..3653898f465f 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -729,9 +729,9 @@ void xprt_force_disconnect(struct rpc_xprt *xprt)
 	/* Try to schedule an autoclose RPC call */
 	if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
 		queue_work(xprtiod_workqueue, &xprt->task_cleanup);
-	else if (xprt->snd_task)
+	else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
 		rpc_wake_up_queued_task_set_status(&xprt->pending,
-				xprt->snd_task, -ENOTCONN);
+						   xprt->snd_task, -ENOTCONN);
 	spin_unlock(&xprt->transport_lock);
 }
 EXPORT_SYMBOL_GPL(xprt_force_disconnect);
@@ -820,6 +820,7 @@ bool xprt_lock_connect(struct rpc_xprt *xprt,
 		goto out;
 	if (xprt->snd_task != task)
 		goto out;
+	set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 	xprt->snd_task = cookie;
 	ret = true;
 out:
@@ -835,6 +836,7 @@ void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
 	if (!test_bit(XPRT_LOCKED, &xprt->state))
 		goto out;
 	xprt->snd_task =NULL;
+	clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
 	xprt->ops->release_xprt(xprt, NULL);
 	xprt_schedule_autodisconnect(xprt);
 out:
-- 
2.30.2