[$] The trouble with struct sockaddr's fake flexible array

Flexible arrays — arrays that are declared as the final member of a
structure and which have a size determined at run time — have long drawn
the attention of developers seeking to harden the kernel against
buffer-overflow vulnerabilities. These arrays have reliably been a source
of bugs, so anything that can be done to ensure that operations on them
stay within bounds is a welcome improvement. While many improvements,
including the recent counted-by work, have
been made, one of the most difficult cases remains. Now, however,
developers who are interested in using recent compiler bounds-checking
features are trying to get a handle on struct sockaddr.