patches/kernel/0163-x86-Kconfig-Limit-NR_CPUS-on-32-bit-to-a-sane-amount.patch

   1 From 883f164f2205159613e17e6550c7ff44cef0ff01 Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Wed, 20 Dec 2017 18:02:34 +0100
   4 Subject: [PATCH 163/241] x86/Kconfig: Limit NR_CPUS on 32-bit to a sane amount
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5754
  10
  11 The recent cpu_entry_area changes fail to compile on 32-bit when BIGSMP=y
  12 and NR_CPUS=512, because the fixmap area becomes too big.
  13
  14 Limit the number of CPUs with BIGSMP to 64, which is already way to big for
  15 32-bit, but it's at least a working limitation.
  16
  17 We performed a quick survey of 32-bit-only machines that might be affected
  18 by this change negatively, but found none.
  19
  20 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  21 Cc: Andy Lutomirski <luto@kernel.org>
  22 Cc: Borislav Petkov <bp@alien8.de>
  23 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  24 Cc: H. Peter Anvin <hpa@zytor.com>
  25 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  26 Cc: Juergen Gross <jgross@suse.com>
  27 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  28 Cc: Peter Zijlstra <peterz@infradead.org>
  29 Cc: linux-kernel@vger.kernel.org
  30 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  31 (cherry picked from commit 7bbcbd3d1cdcbacd0f9f8dc4c98d550972f1ca30)
  32 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  33 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  34 (cherry picked from commit 8ea88ee6f0d058835bfb5685be1ec1beb51177c2)
  35 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  36 ---
  37  arch/x86/Kconfig | 3 ++-
  38  1 file changed, 2 insertions(+), 1 deletion(-)
  39
  40 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
  41 index 8b5499bb24bb..51003e53e738 100644
  42 --- a/arch/x86/Kconfig
  43 +++ b/arch/x86/Kconfig
  44 @@ -923,7 +923,8 @@ config MAXSMP
  45  config NR_CPUS
  46         int "Maximum number of CPUs" if SMP && !MAXSMP
  47         range 2 8 if SMP && X86_32 && !X86_BIGSMP
  48 -       range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
  49 +       range 2 64 if SMP && X86_32 && X86_BIGSMP
  50 +       range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
  51         range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
  52         default "1" if !SMP
  53         default "8192" if MAXSMP
  54 --
  55 2.14.2
  56