can: bcm/raw: fix msg_namelen values depending on CAN_REQUIRED_SIZE

Since commit f5223e9e ("can: extend sockaddr_can to include j1939
members") the sockaddr_can has been extended in size and a new
CAN_REQUIRED_SIZE macro has been introduced to calculate the protocol
specific needed size.

The ABI for the msg_name and msg_namelen has not been adapted to the
new CAN_REQUIRED_SIZE macro for the other CAN protocols which leads to
a problem when an existing binary reads the (increased) struct
sockaddr_can in msg_name.

Fixes: f5223e9e ("can: extend sockaddr_can to include j1939 members")
Reported-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
Acked-by: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>
Link: https://lore.kernel.org/linux-can/1135648123.112255.1616613706554.JavaMail.zimbra@nod.at/T/#t
Link: https://lore.kernel.org/r/20210325125850.1620-1-socketcan@hartkopp.netSigned-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

net/can/bcm.c

@@ -86,6 +86,8 @@ MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
 MODULE_ALIAS("can-proto-2");
 
+#define BCM_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_ifindex)
+
 /*
  * easy access to the first 64 bit of can(fd)_frame payload. cp->data is
  * 64 bit aligned so the offset has to be multiples of 8 which is ensured
@@ -1292,7 +1294,7 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 		/* no bound device as default => check msg_name */
 		DECLARE_SOCKADDR(struct sockaddr_can *, addr, msg->msg_name);
 
-		if (msg->msg_namelen < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+		if (msg->msg_namelen < BCM_MIN_NAMELEN)
 			return -EINVAL;
 
 		if (addr->can_family != AF_CAN)
@@ -1534,7 +1536,7 @@ static int bcm_connect(struct socket *sock, struct sockaddr *uaddr, int len,
 	struct net *net = sock_net(sk);
 	int ret = 0;
 
-	if (len < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+	if (len < BCM_MIN_NAMELEN)
 		return -EINVAL;
 
 	lock_sock(sk);
@@ -1616,8 +1618,8 @@ static int bcm_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	sock_recv_ts_and_drops(msg, sk, skb);
 
 	if (msg->msg_name) {
-		__sockaddr_check_size(sizeof(struct sockaddr_can));
-		msg->msg_namelen = sizeof(struct sockaddr_can);
+		__sockaddr_check_size(BCM_MIN_NAMELEN);
+		msg->msg_namelen = BCM_MIN_NAMELEN;
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
 	}
 

net/can/raw.c

@@ -60,6 +60,8 @@ MODULE_LICENSE("Dual BSD/GPL");
 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
 MODULE_ALIAS("can-proto-1");
 
+#define RAW_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_ifindex)
+
 #define MASK_ALL 0
 
 /* A raw socket has a list of can_filters attached to it, each receiving
@@ -394,7 +396,7 @@ static int raw_bind(struct socket *sock, struct sockaddr *uaddr, int len)
 	int err = 0;
 	int notify_enetdown = 0;
 
-	if (len < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+	if (len < RAW_MIN_NAMELEN)
 		return -EINVAL;
 	if (addr->can_family != AF_CAN)
 		return -EINVAL;
@@ -475,11 +477,11 @@ static int raw_getname(struct socket *sock, struct sockaddr *uaddr,
 	if (peer)
 		return -EOPNOTSUPP;
 
-	memset(addr, 0, sizeof(*addr));
+	memset(addr, 0, RAW_MIN_NAMELEN);
 	addr->can_family  = AF_CAN;
 	addr->can_ifindex = ro->ifindex;
 
-	return sizeof(*addr);
+	return RAW_MIN_NAMELEN;
 }
 
 static int raw_setsockopt(struct socket *sock, int level, int optname,
@@ -739,7 +741,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	if (msg->msg_name) {
 		DECLARE_SOCKADDR(struct sockaddr_can *, addr, msg->msg_name);
 
-		if (msg->msg_namelen < CAN_REQUIRED_SIZE(*addr, can_ifindex))
+		if (msg->msg_namelen < RAW_MIN_NAMELEN)
 			return -EINVAL;
 
 		if (addr->can_family != AF_CAN)
@@ -832,8 +834,8 @@ static int raw_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
 	sock_recv_ts_and_drops(msg, sk, skb);
 
 	if (msg->msg_name) {
-		__sockaddr_check_size(sizeof(struct sockaddr_can));
-		msg->msg_namelen = sizeof(struct sockaddr_can);
+		__sockaddr_check_size(RAW_MIN_NAMELEN);
+		msg->msg_namelen = RAW_MIN_NAMELEN;
 		memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
 	}