On Fri, Nov 3, 2017 at 5:24 PM, Al Viro <[email protected]> wrote: > On Fri, Nov 03, 2017 at 05:14:05PM -0700, Kees Cook wrote: >> > x86 turns out to be easier since the safe and unsafe paths are mostly >> > disjoint so we don't have to worry about gcc optimizing out access_ok. >> > I tweaked the Kconfig to someting a bit more generic. >> > >> > The size increase was ~8K in text with a config I tested. >> >> Specifically, this feature would have caught the waitid() bug in 4.13 >> immediately. > > You mean, as soon as waitid() was given a kernel address. At which point > you'd get a shiny way to generate a BUG(), and if something like that > happened under a mutex - it's even more fun...
Nope, any usage at all would BUG. This would have been immediately noticed. :) -Kees -- Kees Cook Pixel Security
