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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,
        Matthieu Baerts <matthieu.baerts@tessares.net>,
        Geliang Tang <geliang.tang@suse.com>,
        Mat Martineau <mathew.j.martineau@linux.intel.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 350/846] mptcp: fix a DSS option writing error
Date:   Mon, 24 Jan 2022 19:37:47 +0100
Message-Id: <20220124184113.027769675@linuxfoundation.org>
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From: Geliang Tang <geliang.tang@suse.com>

[ Upstream commit 110b6d1fe98fd7af9893992459b651594d789293 ]

'ptr += 1;' was omitted in the original code.

If the DSS is the last option -- which is what we have most of the
time -- that's not an issue. But it is if we need to send something else
after like a RM_ADDR or an MP_PRIO.

Fixes: 1bff1e43a30e ("mptcp: optimize out option generation")
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/mptcp/options.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index f69a1cadb13fc..e515ba9ccb5d8 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -1321,6 +1321,7 @@ void mptcp_write_options(__be32 *ptr, const struct tcp_sock *tp,
 				put_unaligned_be32(mpext->data_len << 16 |
 						   TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
 			}
+			ptr += 1;
 		}
 	} else if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
 		    OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
-- 
2.34.1