Messages in this thread | | | From | Kees Cook <> | Date | Thu, 16 Jun 2016 10:24:24 -0700 | Subject | Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) |
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On Wed, Jun 15, 2016 at 5:28 PM, Andy Lutomirski <luto@kernel.org> wrote: > Since the dawn of time, a kernel stack overflow has been a real PITA > to debug, has caused nondeterministic crashes some time after the > actual overflow, and has generally been easy to exploit for root. > > With this series, arches can enable HAVE_ARCH_VMAP_STACK. Arches > that enable it (just x86 for now) get virtually mapped stacks with > guard pages. This causes reliable faults when the stack overflows. > > If the arch implements it well, we get a nice OOPS on stack overflow > (as opposed to panicing directly or otherwise exploding badly). On > x86, the OOPS is nice, has a usable call trace, and the overflowing > task is killed cleanly. > > This does not address interrupt stacks. > > Andy Lutomirski (12): > x86/cpa: In populate_pgd, don't set the pgd entry until it's populated > x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately > mm: Track NR_KERNEL_STACK in pages instead of number of stacks > mm: Move memcg stack accounting to account_kernel_stack > fork: Add generic vmalloced stack support > x86/die: Don't try to recover from an OOPS on a non-default stack > x86/dumpstack: When OOPSing, rewind the stack before do_exit > x86/dumpstack: When dumping stack bytes due to OOPS, start with > regs->sp > x86/dumpstack: Try harder to get a call trace on stack overflow > x86/dumpstack/64: Handle faults when printing the "Stack:" part of an > OOPS > x86/mm/64: Enable vmapped stacks > x86/mm: Improve stack-overflow #PF handling > > Ingo Molnar (1): > x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() > > arch/Kconfig | 12 ++++++++++ > arch/x86/Kconfig | 1 + > arch/x86/entry/entry_32.S | 11 +++++++++ > arch/x86/entry/entry_64.S | 11 +++++++++ > arch/x86/include/asm/switch_to.h | 28 +++++++++++++++++++++- > arch/x86/include/asm/traps.h | 6 +++++ > arch/x86/kernel/dumpstack.c | 17 +++++++++++++- > arch/x86/kernel/dumpstack_32.c | 4 +++- > arch/x86/kernel/dumpstack_64.c | 16 ++++++++++--- > arch/x86/kernel/traps.c | 32 +++++++++++++++++++++++++ > arch/x86/mm/fault.c | 39 ++++++++++++++++++++++++++++++ > arch/x86/mm/init_64.c | 27 --------------------- > arch/x86/mm/pageattr.c | 7 +++++- > arch/x86/mm/tlb.c | 15 ++++++++++++ > fs/proc/meminfo.c | 2 +- > kernel/fork.c | 51 ++++++++++++++++++++++++++++++---------- > mm/page_alloc.c | 3 +-- > 17 files changed, 233 insertions(+), 49 deletions(-)
This is great, thanks! This helps the up-coming usercopy self-protection code, and makes stack overflows a much less interesting target for attackers.
-Kees
-- Kees Cook Chrome OS & Brillo Security
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