Messages in this thread Patch in this message | | | Date | Mon, 8 Jan 2018 12:42:41 -0800 | From | tip-bot for Dave Hansen <> | Subject | [tip:x86/pti] x86/tboot: Unbreak tboot with PTI enabled |
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Commit-ID: 262b6b30087246abf09d6275eb0c0dc421bcbe38 Gitweb: https://git.kernel.org/tip/262b6b30087246abf09d6275eb0c0dc421bcbe38 Author: Dave Hansen <dave.hansen@linux.intel.com> AuthorDate: Sat, 6 Jan 2018 18:41:14 +0100 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Mon, 8 Jan 2018 17:29:18 +0100
x86/tboot: Unbreak tboot with PTI enabled
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> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20180108102805.GK25546@redhat.com --- arch/x86/kernel/tboot.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c index a4eb279..75869a4 100644 --- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -127,6 +127,7 @@ static int map_tboot_page(unsigned long vaddr, unsigned long pfn, 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;
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