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

From 883f164f2205159613e17e6550c7ff44cef0ff01 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Wed, 20 Dec 2017 18:02:34 +0100
Subject: [PATCH 163/232] x86/Kconfig: Limit NR_CPUS on 32-bit to a sane amount
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CVE-2017-5754

The recent cpu_entry_area changes fail to compile on 32-bit when BIGSMP=y
and NR_CPUS=512, because the fixmap area becomes too big.

Limit the number of CPUs with BIGSMP to 64, which is already way to big for
32-bit, but it's at least a working limitation.

We performed a quick survey of 32-bit-only machines that might be affected
by this change negatively, but found none.

Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
(cherry picked from commit 7bbcbd3d1cdcbacd0f9f8dc4c98d550972f1ca30)
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Kleber Sacilotto de Souza <[email protected]>
(cherry picked from commit 8ea88ee6f0d058835bfb5685be1ec1beb51177c2)
Signed-off-by: Fabian Grünbichler <[email protected]>
---
 arch/x86/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8b5499bb24bb..51003e53e738 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -923,7 +923,8 @@ config MAXSMP
 config NR_CPUS
 	int "Maximum number of CPUs" if SMP && !MAXSMP
 	range 2 8 if SMP && X86_32 && !X86_BIGSMP
-	range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK
+	range 2 64 if SMP && X86_32 && X86_BIGSMP
+	range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK && X86_64
 	range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64
 	default "1" if !SMP
 	default "8192" if MAXSMP
-- 
2.14.2