From: Geliang Tang <geliangtang@gmail.com>
Date: Mon, 8 Jun 2020 10:47:54 +0000 (+0800)
Subject: mptcp: bugfix for RM_ADDR option parsing
X-Git-Tag: v5.8-rc1~3^2~33
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8e60eed6b38e464e8c9d68f9caecafaa554dffe0;p=thirdparty%2Flinux.git

mptcp: bugfix for RM_ADDR option parsing

In MPTCPOPT_RM_ADDR option parsing, the pointer "ptr" pointed to the
"Subtype" octet, the pointer "ptr+1" pointed to the "Address ID" octet:

  +-------+-------+---------------+
  |Subtype|(resvd)|   Address ID  |
  +-------+-------+---------------+
  |               |
 ptr            ptr+1

We should set mp_opt->rm_id to the value of "ptr+1", not "ptr". This patch
will fix this bug.

Fixes: 3df523ab582c ("mptcp: Add ADD_ADDR handling")
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 01f1f4cf4902a..490b92534afc3 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -273,6 +273,8 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 		if (opsize != TCPOLEN_MPTCP_RM_ADDR_BASE)
 			break;
 
+		ptr++;
+
 		mp_opt->rm_addr = 1;
 		mp_opt->rm_id = *ptr++;
 		pr_debug("RM_ADDR: id=%d", mp_opt->rm_id);