fastd v21

This is a critical bugfix release. All users of fastd v20 must update.


The new buffer management of fastd v20 revealed that received packets with an invalid type code were handled incorrectly, leaking the packet buffer. This lead to an assertion failure as soon as the buffer pool was empty, crashing fastd.

Older versions of fastd are affected as well, but display a different behaviour: instead of crashing, the buffer leaks will manifest as a regular memory leak. This can still be used for Denial of Service attacks, so a patch for older versions will be provided, for the case that users can’t or do not want to update to a newer version yet.