Pull hardened usercopy fixes from Kees Cook:
- avoid signed math problems on unexpected compilers
- avoid false positives at very end of kernel text range checks
* tag 'usercopy-v4.8-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
usercopy: fix overlap check for kernel text
usercopy: avoid potentially undefined behavior in pointer math