[PATCH net-next 2/2] mctp: handle the struct sockaddr_mctp_ext padding field

From: Eugene Syromiatnikov
Date: Mon Nov 01 2021 - 13:55:06 EST


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@xxxxxxxxxx>
---
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