netdev - [PATCH net-next 12/12] mptcp: Safely store sequence number when sending data

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Message-Id: <20200728221210.92841-13-mathew.j.martineau@linux.intel.com>
Date:   Tue, 28 Jul 2020 15:12:10 -0700
From:   Mat Martineau <mathew.j.martineau@...ux.intel.com>
To:     netdev@...r.kernel.org
Cc:     Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        mptcp@...ts.01.org, matthieu.baerts@...sares.net, pabeni@...hat.com
Subject: [PATCH net-next 12/12] mptcp: Safely store sequence number when sending data

The MPTCP socket's write_seq member can be read without the msk lock
held, so use WRITE_ONCE() to store it.

Signed-off-by: Mat Martineau <mathew.j.martineau@...ux.intel.com>
---
 net/mptcp/protocol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f2455a68d231..687f0bea2b35 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -793,7 +793,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 out:
 	if (!retransmission)
 		pfrag->offset += frag_truesize;
-	*write_seq += ret;
+	WRITE_ONCE(*write_seq, *write_seq + ret);
 	mptcp_subflow_ctx(ssk)->rel_write_seq += ret;
 
 	return ret;
-- 
2.28.0