This is a note to let you know that I've just added the patch titled
x86/pti: Unbreak EFI old_memmap
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-pti-unbreak-efi-old_memmap.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@xxxxxxxxxxxxxxx> know about it.
>From de53c3786a3ce162a1c815d0c04c766c23ec9c0a Mon Sep 17 00:00:00 2001
From: Jiri Kosina <jkosina@xxxxxxx>
Date: Fri, 5 Jan 2018 22:35:41 +0100
Subject: x86/pti: Unbreak EFI old_memmap
From: Jiri Kosina <jkosina@xxxxxxx>
commit de53c3786a3ce162a1c815d0c04c766c23ec9c0a upstream.
EFI_OLD_MEMMAP's efi_call_phys_prolog() calls set_pgd() with swapper PGD that
has PAGE_USER set, which makes PTI set NX on it, and therefore EFI can't
execute it's code.
Fix that by forcefully clearing _PAGE_NX from the PGD (this can't be done
by the pgprot API).
_PAGE_NX will be automatically reintroduced in efi_call_phys_epilog(), as
_set_pgd() will again notice that this is _PAGE_USER, and set _PAGE_NX on
it.
Tested-by: Dimitri Sivanich <sivanich@xxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1801052215460.11852@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/platform/efi/efi_64.c | 2 ++
1 file changed, 2 insertions(+)
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -134,7 +134,9 @@ pgd_t * __init efi_call_phys_prolog(void
pud[j] = *pud_offset(p4d_k, vaddr);
}
}
+ pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX;
}
+
out:
__flush_tlb_all();
Patches currently in stable-queue which might be from jkosina@xxxxxxx are
queue-4.14/x86-pti-unbreak-efi-old_memmap.patch