62 lines
2.1 KiB
Diff
62 lines
2.1 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Jiri Kosina <jkosina@suse.cz>
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Date: Fri, 5 Jan 2018 22:35:41 +0100
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Subject: [PATCH] x86/pti: Unbreak EFI old_memmap
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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CVE-2017-5754
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EFI_OLD_MEMMAP's efi_call_phys_prolog() calls set_pgd() with swapper PGD that
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has PAGE_USER set, which makes PTI set NX on it, and therefore EFI can't
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execute it's code.
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Fix that by forcefully clearing _PAGE_NX from the PGD (this can't be done
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by the pgprot API).
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_PAGE_NX will be automatically reintroduced in efi_call_phys_epilog(), as
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_set_pgd() will again notice that this is _PAGE_USER, and set _PAGE_NX on
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it.
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Tested-by: Dimitri Sivanich <sivanich@hpe.com>
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Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
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Cc: Andrea Arcangeli <aarcange@redhat.com>
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Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Matt Fleming <matt@codeblueprint.co.uk>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Cc: linux-efi@vger.kernel.org
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Cc: stable@vger.kernel.org
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Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1801052215460.11852@cbobk.fhfr.pm
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(cherry picked from commit de53c3786a3ce162a1c815d0c04c766c23ec9c0a)
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Signed-off-by: Andy Whitcroft <apw@canonical.com>
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Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
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(cherry picked from commit 31afacd8089f54061e718e5d491f11747755c503)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/platform/efi/efi_64.c | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
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index b104224d3d6c..987a38e82f73 100644
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--- a/arch/x86/platform/efi/efi_64.c
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+++ b/arch/x86/platform/efi/efi_64.c
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@@ -133,7 +133,9 @@ pgd_t * __init efi_call_phys_prolog(void)
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pud[j] = *pud_offset(p4d_k, vaddr);
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}
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}
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+ pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX;
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}
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+
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out:
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__flush_tlb_all();
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--
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2.14.2
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