[PATCH AUTOSEL 4.9 11/25] mISDN: Check address length before reading address family

[Sasha Levin]

From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 238ffdc49ef98b15819cfd5e3fb23194e3ea3d39 ]

KMSAN will complain if valid address length passed to bind() is shorter
than sizeof("struct sockaddr_mISDN"->family) bytes.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/isdn/mISDN/socket.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/isdn/mISDN/socket.c b/drivers/isdn/mISDN/socket.c
index 99e5f9751e8b..f96b8f2bdf74 100644
--- a/drivers/isdn/mISDN/socket.c
+++ b/drivers/isdn/mISDN/socket.c
@@ -712,10 +712,10 @@ base_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 	struct sock *sk = sock->sk;
 	int err = 0;
 
-	if (!maddr || maddr->family != AF_ISDN)
+	if (addr_len < sizeof(struct sockaddr_mISDN))
 		return -EINVAL;
 
-	if (addr_len < sizeof(struct sockaddr_mISDN))
+	if (!maddr || maddr->family != AF_ISDN)
 		return -EINVAL;
 
 	lock_sock(sk);
-- 
2.20.1