Affected: PyPI: dnspython

### Summary

A maliciously crafted zone file could use a WKS record to consume excessive memory and CPU, possibly causing the process to exit due to memory exhaustion.

### Details

The `from_text()` parser does not check that a WKS record service number is between 0 and 65535 inclusive. It then uses this number to resize the bitmap to accommodate a bit with that offset. This can cause extremely large memory allocations, and also extends the array very inefficiently, wasting CPU.

### Proof of concept

This demonstrates the failure to limit the service number, though with a value that does not cause excessive memory or CPU consumption.

``` rd = dns.rdata.from_text("IN", "WKS", "10.0.0.1 udp 65536") ```

### Impact

If dnspython is used to read zonefile format where the attacker can control the type and rdata text, the program may consume excessive memory or CPU, denying service.