4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dave Hansen <[email protected]> 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 <[email protected]> Signed-off-by: Andrea Arcangeli <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> Cc: Alan Cox <[email protected]> Cc: Tim Chen <[email protected]> Cc: Jon Masters <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Andi Kleen <[email protected]> Cc: Jeff Law <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: David <[email protected]> Cc: Nick Clifton <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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;
