This is a note to let you know that I've just added the patch titled

x86/tboot: Unbreak tboot with PTI enabled

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-tboot-unbreak-tboot-with-pti-enabled.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 262b6b30087246abf09d6275eb0c0dc421bcbe38 Mon Sep 17 00:00:00 2001

From: Dave Hansen dave.hansen@linux.intel.com Date: Sat, 6 Jan 2018 18:41:14 +0100 Subject: x86/tboot: Unbreak tboot with PTI enabled

From: Dave Hansen dave.hansen@linux.intel.com

commit 262b6b30087246abf09d6275eb0c0dc421bcbe38 upstream.

This is another case similar to what EFI does: create a new set of page tables, map some code at a low address, and jump to it. PTI mistakes this low address for userspace and mistakenly marks it non-executable in an effort to make it unusable for userspace.

Undo the poison to allow execution.

Fixes: 385ce0ea4c07 ("x86/mm/pti: Add Kconfig") Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Signed-off-by: Andrea Arcangeli aarcange@redhat.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Alan Cox gnomes@lxorguk.ukuu.org.uk Cc: Tim Chen tim.c.chen@linux.intel.com Cc: Jon Masters jcm@redhat.com Cc: Dave Hansen dave.hansen@intel.com Cc: Andi Kleen andi@firstfloor.org Cc: Jeff Law law@redhat.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Greg Kroah-Hartman gregkh@linux-foundation.org Cc: David" dwmw@amazon.co.uk Cc: Nick Clifton nickc@redhat.com Link: https://lkml.kernel.org/r/20180108102805.GK25546@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kernel/tboot.c | 1 + 1 file changed, 1 insertion(+)

--- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -127,6 +127,7 @@ static int map_tboot_page(unsigned long p4d = p4d_alloc(&tboot_mm, pgd, vaddr); if (!p4d) return -1; + pgd->pgd &= ~_PAGE_NX; pud = pud_alloc(&tboot_mm, p4d, vaddr); if (!pud) return -1;

Patches currently in stable-queue which might be from dave.hansen@linux.intel.com are

queue-4.14/x86-pti-unbreak-efi-old_memmap.patch queue-4.14/x86-documentation-add-pti-description.patch queue-4.14/x86-tboot-unbreak-tboot-with-pti-enabled.patch