[PATCH 0/7] x86: uaccess hardening, easy part

From: Andy Lutomirski
Date: Tue May 24 2016 - 18:48:54 EST

This series hardens x86's uaccess code a bit. It adds warnings for
some screwups, adds an OOPS for a major exploitable screwup, and it
improves debuggability a bit by indicating non-default fs in oopses.

It shouldn't cause any new OOPSes except in the particularly
dangerous case where the kernel faults on a kernel address under
USER_DS, which indicates that an access_ok is missing and is likely
to be easily exploitable -- OOPSing will make it harder to exploit.

I have some draft patches to force OOPSes on user address accesses
under KERNEL_DS (which is a big no-no), but I'd rather make those
warn instead of OOPSing, and I don't have a good implementation of
that yet. Those patches aren't part of this series.

Andy Lutomirski (7):
x86/xen: Simplify set_aliased_prot
x86/extable: Pass error_code and an extra unsigned long to exhandlers
x86/uaccess: Give uaccess faults their own handler
x86/dumpstack: If addr_limit is non-default, display it
x86/uaccess: Warn on uaccess faults other than #PF
x86/uaccess: Don't fix up USER_DS uaccess faults to kernel addresses
x86/uaccess: OOPS or warn on a fault with KERNEL_DS and

arch/x86/include/asm/uaccess.h | 19 ++++---
arch/x86/kernel/cpu/mcheck/mce.c | 2 +-
arch/x86/kernel/dumpstack_32.c | 4 ++
arch/x86/kernel/dumpstack_64.c | 5 ++
arch/x86/kernel/kprobes/core.c | 6 +-
arch/x86/kernel/traps.c | 6 +-
arch/x86/lib/getuser.S | 12 ++--
arch/x86/lib/putuser.S | 10 ++--
arch/x86/mm/extable.c | 120 ++++++++++++++++++++++++++++++++++-----
arch/x86/mm/fault.c | 2 +-
arch/x86/xen/enlighten.c | 4 +-
11 files changed, 145 insertions(+), 45 deletions(-)