On Wed, Jan 23, 2019 at 1:04 PM Greg KH [off-list ref] wrote:

On Wed, Jan 23, 2019 at 03:03:47AM -0800, Kees Cook wrote:

quoted

Variables declared in a switch statement before any case statements
cannot be initialized, so move all instances out of the switches.
After this, future always-initialized stack variables will work
and not throw warnings like this:

fs/fcntl.c: In function ‘send_sigio_to_task’:
fs/fcntl.c:738:13: warning: statement will never be executed [-Wswitch-unreachable]
   siginfo_t si;
             ^~

That's a pain, so this means we can't have any new variables in { }
scope except for at the top of a function?

AFAICS this only applies to switch statements (because they jump to a
case and don't execute stuff at the start of the block), not blocks
after if/while/... .

That's going to be a hard thing to keep from happening over time, as
this is valid C :(