84 lines
2.9 KiB
Diff
84 lines
2.9 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: Mon, 4 Dec 2017 15:07:38 +0100
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Subject: [PATCH] x86/mm/pti: Allow NX poison to be set in p4d/pgd
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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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With PAGE_TABLE_ISOLATION the user portion of the kernel page tables is
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poisoned with the NX bit so if the entry code exits with the kernel page
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tables selected in CR3, userspace crashes.
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But doing so trips the p4d/pgd_bad() checks. Make sure it does not do
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that.
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Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Borislav Petkov <bp@suse.de>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: Brian Gerst <brgerst@gmail.com>
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Cc: David Laight <David.Laight@aculab.com>
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Cc: Denys Vlasenko <dvlasenk@redhat.com>
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Cc: Eduardo Valentin <eduval@amazon.com>
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Cc: Greg KH <gregkh@linuxfoundation.org>
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Cc: H. Peter Anvin <hpa@zytor.com>
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Cc: Josh Poimboeuf <jpoimboe@redhat.com>
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Cc: Juergen Gross <jgross@suse.com>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Will Deacon <will.deacon@arm.com>
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Cc: aliguori@amazon.com
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Cc: daniel.gruss@iaik.tugraz.at
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Cc: hughd@google.com
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Cc: keescook@google.com
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Cc: linux-kernel@vger.kernel.org
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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(cherry picked from commit 1c4de1ff4fe50453b968579ee86fac3da80dd783)
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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 889a8bd0e57e39e7ce337e87c55fa59c09644d4e)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/include/asm/pgtable.h | 14 ++++++++++++--
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1 file changed, 12 insertions(+), 2 deletions(-)
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diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
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index abbb47c75467..3ef8415b2358 100644
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--- a/arch/x86/include/asm/pgtable.h
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+++ b/arch/x86/include/asm/pgtable.h
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@@ -831,7 +831,12 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
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static inline int p4d_bad(p4d_t p4d)
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{
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- return (p4d_flags(p4d) & ~(_KERNPG_TABLE | _PAGE_USER)) != 0;
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+ unsigned long ignore_flags = _KERNPG_TABLE | _PAGE_USER;
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+
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+ if (IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
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+ ignore_flags |= _PAGE_NX;
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+
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+ return (p4d_flags(p4d) & ~ignore_flags) != 0;
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}
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#endif /* CONFIG_PGTABLE_LEVELS > 3 */
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@@ -865,7 +870,12 @@ static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
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static inline int pgd_bad(pgd_t pgd)
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{
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- return (pgd_flags(pgd) & ~_PAGE_USER) != _KERNPG_TABLE;
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+ unsigned long ignore_flags = _PAGE_USER;
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+
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+ if (IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
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+ ignore_flags |= _PAGE_NX;
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+
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+ return (pgd_flags(pgd) & ~ignore_flags) != _KERNPG_TABLE;
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}
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static inline int pgd_none(pgd_t pgd)
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--
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2.14.2
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