linux-kernel - [PATCH net-next 2/2] mctp: handle the struct sockaddr_mctp

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Date:   Mon, 1 Nov 2021 18:54:53 +0100
From:   Eugene Syromiatnikov <esyr@...hat.com>
To:     Jeremy Kerr <jk@...econstruct.com.au>,
        Matt Johnston <matt@...econstruct.com.au>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 2/2] mctp: handle the struct sockaddr_mctp_ext
 padding field

struct sockaddr_mctp_ext.__smctp_paddin0 has to be checked for being set
to zero, otherwise it cannot be utilised in the future.

Complements: 99ce45d5e7dbde39 ("mctp: Implement extended addressing")
Signed-off-by: Eugene Syromiatnikov <esyr@...hat.com>
---
 net/mctp/af_mctp.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/mctp/af_mctp.c b/net/mctp/af_mctp.c
index bc88159..6cd1308 100644
--- a/net/mctp/af_mctp.c
+++ b/net/mctp/af_mctp.c
@@ -39,6 +39,13 @@ static bool mctp_sockaddr_is_ok(const struct sockaddr_mctp *addr)
 	return !addr->__smctp_pad0 && !addr->__smctp_pad1;
 }
 
+static bool mctp_sockaddr_ext_is_ok(const struct sockaddr_mctp_ext *addr)
+{
+	return !addr->__smctp_pad0[0]
+	       && !addr->__smctp_pad0[1]
+	       && !addr->__smctp_pad0[2];
+}
+
 static int mctp_bind(struct socket *sock, struct sockaddr *addr, int addrlen)
 {
 	struct sock *sk = sock->sk;
@@ -135,7 +142,8 @@ static int mctp_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 		DECLARE_SOCKADDR(struct sockaddr_mctp_ext *,
 				 extaddr, msg->msg_name);
 
-		if (extaddr->smctp_halen > sizeof(cb->haddr)) {
+		if (!mctp_sockaddr_ext_is_ok(extaddr)
+		    || extaddr->smctp_halen > sizeof(cb->haddr)) {
 			rc = -EINVAL;
 			goto err_free;
 		}
@@ -224,6 +232,7 @@ static int mctp_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 			msg->msg_namelen = sizeof(*ae);
 			ae->smctp_ifindex = cb->ifindex;
 			ae->smctp_halen = cb->halen;
+			memset(ae->__smctp_pad0, 0x0, sizeof(ae->__smctp_pad0));
 			memset(ae->smctp_haddr, 0x0, sizeof(ae->smctp_haddr));
 			memcpy(ae->smctp_haddr, cb->haddr, cb->halen);
 		}
-- 
2.1.4