From: Andy Lutomirski <luto@kernel.org>
Date: Tue, 8 Aug 2017 02:43:13 +0000 (-0700)
Subject: x86/asm/64: Clear AC on NMI entries
X-Git-Tag: archive/raspbian/4.9.51-1+rpi1~7^2~256
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=10d5bf2f6928e3d333cbf82d970d4a057686f9f9;p=linux-4.9.git

x86/asm/64: Clear AC on NMI entries

commit e93c17301ac55321fc18e0f8316e924e58a83c8c upstream.

This closes a hole in our SMAP implementation.

This patch comes from grsecurity. Good catch!

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/314cc9f294e8f14ed85485727556ad4f15bb1659.1502159503.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index ef766a358b37..e7b0e7ff4c58 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1215,6 +1215,8 @@ ENTRY(nmi)
 	 * other IST entries.
 	 */
 
+	ASM_CLAC
+
 	/* Use %rdx as our temp variable throughout */
 	pushq	%rdx