54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Dave Hansen <dave.hansen@linux.intel.com>
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Date: Sat, 6 Jan 2018 18:41:14 +0100
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Subject: [PATCH] x86/tboot: Unbreak tboot with PTI enabled
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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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commit 262b6b30087246abf09d6275eb0c0dc421bcbe38 upstream.
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This is another case similar to what EFI does: create a new set of
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page tables, map some code at a low address, and jump to it. PTI
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mistakes this low address for userspace and mistakenly marks it
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non-executable in an effort to make it unusable for userspace.
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Undo the poison to allow execution.
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Fixes: 385ce0ea4c07 ("x86/mm/pti: Add Kconfig")
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Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
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Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
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Cc: Tim Chen <tim.c.chen@linux.intel.com>
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Cc: Jon Masters <jcm@redhat.com>
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Cc: Dave Hansen <dave.hansen@intel.com>
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Cc: Andi Kleen <andi@firstfloor.org>
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Cc: Jeff Law <law@redhat.com>
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Cc: Paolo Bonzini <pbonzini@redhat.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
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Cc: David" <dwmw@amazon.co.uk>
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Cc: Nick Clifton <nickc@redhat.com>
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Link: https://lkml.kernel.org/r/20180108102805.GK25546@redhat.com
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/kernel/tboot.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
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index a2486f444073..8337730f0956 100644
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--- a/arch/x86/kernel/tboot.c
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+++ b/arch/x86/kernel/tboot.c
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@@ -127,6 +127,7 @@ static int map_tboot_page(unsigned long vaddr, unsigned long pfn,
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p4d = p4d_alloc(&tboot_mm, pgd, vaddr);
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if (!p4d)
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return -1;
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+ pgd->pgd &= ~_PAGE_NX;
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pud = pud_alloc(&tboot_mm, p4d, vaddr);
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if (!pud)
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return -1;
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--
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2.14.2
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