2018-01-15 14:26:15 +03:00
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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2018-01-06 17:13:39 +03:00
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Wed, 20 Dec 2017 18:02:34 +0100
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2018-01-15 14:26:15 +03:00
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Subject: [PATCH] x86/Kconfig: Limit NR_CPUS on 32-bit to a sane amount
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2018-01-06 17:13:39 +03:00
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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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The recent cpu_entry_area changes fail to compile on 32-bit when BIGSMP=y
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and NR_CPUS=512, because the fixmap area becomes too big.
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Limit the number of CPUs with BIGSMP to 64, which is already way to big for
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32-bit, but it's at least a working limitation.
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We performed a quick survey of 32-bit-only machines that might be affected
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by this change negatively, but found none.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Cc: Andy Lutomirski <luto@kernel.org>
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Cc: Borislav Petkov <bp@alien8.de>
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Cc: Dave Hansen <dave.hansen@linux.intel.com>
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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: 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 7bbcbd3d1cdcbacd0f9f8dc4c98d550972f1ca30)
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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 8ea88ee6f0d058835bfb5685be1ec1beb51177c2)
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Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
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---
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arch/x86/Kconfig | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
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index 8b5499bb24bb..51003e53e738 100644
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -923,7 +923,8 @@ config MAXSMP
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config NR_CPUS
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int "Maximum number of CPUs" if SMP && !MAXSMP
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range 2 8 if SMP && X86_32 && !X86_BIGSMP
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- range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
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+ range 2 64 if SMP && X86_32 && X86_BIGSMP
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+ range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
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range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
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default "1" if !SMP
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default "8192" if MAXSMP
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--
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2.14.2
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