af_iucv: Move sockaddr length checks to before accessing sa_family in bind and connect handlers

BugLink: https://bugs.launchpad.net/bugs/1810807

[ Upstream commit e3c42b61 ]

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() and connect()
handlers of the AF_IUCV socket. Since neither syscall enforces a minimum
size of the corresponding memory region, very short sockaddrs (zero or
one byte long) result in operating on uninitialized memory while
referencing .sa_family.

Fixes: 52a82e23 ("af_iucv: Validate socket address length in iucv_sock_bind()")
Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
[jwi: removed unneeded null-check for addr]
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/iucv/af_iucv.c

@@ -717,10 +717,8 @@ static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
 	char uid[9];
 
 	/* Verify the input sockaddr */
-	if (!addr || addr->sa_family != AF_IUCV)
-		return -EINVAL;
-
-	if (addr_len < sizeof(struct sockaddr_iucv))
+	if (addr_len < sizeof(struct sockaddr_iucv) ||
+	    addr->sa_family != AF_IUCV)
 		return -EINVAL;
 
 	lock_sock(sk);
@@ -864,7 +862,7 @@ static int iucv_sock_connect(struct socket *sock, struct sockaddr *addr,
 	struct iucv_sock *iucv = iucv_sk(sk);
 	int err;
 
-	if (addr->sa_family != AF_IUCV || alen < sizeof(struct sockaddr_iucv))
+	if (alen < sizeof(struct sockaddr_iucv) || addr->sa_family != AF_IUCV)
 		return -EINVAL;
 
 	if (sk->sk_state != IUCV_OPEN && sk->sk_state != IUCV_BOUND)