4.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andy Lutomirski <[email protected]> commit c739f930be1dd5fd949030e3475a884fe06dae9b upstream. Using PGDIR_SHIFT to identify espfix64 addresses on 5-level systems was wrong, and it resulted in panics due to unhandled double faults. Use P4D_SHIFT instead, which is correct on 4-level and 5-level machines. This fixes a panic when running x86 selftests on 5-level machines. Signed-off-by: Andy Lutomirski <[email protected]> Acked-by: Kirill A. Shutemov <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dave Hansen <[email protected]> Cc: David Laight <[email protected]> Cc: Kees Cook <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Fixes: 1d33b219563f ("x86/espfix: Add support for 5-level paging") Link: http://lkml.kernel.org/r/24c898b4f44fdf8c22d93703850fb384ef87cfdc.1513035461.git.l...@kernel.org Signed-off-by: Ingo Molnar <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/traps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -361,7 +361,7 @@ dotraplinkage void do_double_fault(struc * * No need for ist_enter here because we don't use RCU. */ - if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY && + if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY && regs->cs == __KERNEL_CS && regs->ip == (unsigned long)native_irq_return_iret) {
