netlink: validate addr_len on bind

Otherwise an out of bounds read could happen.

Signed-off-by: Hannes Frederic Sowa <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/netlink/af_netlink.c

···
 	struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 	int err;
 
+	if (addr_len < sizeof(struct sockaddr_nl))
+		return -EINVAL;
+
 	if (nladdr->nl_family != AF_NETLINK)
 		return -EINVAL;