pve-edge-kernel/patches/kernel/0167-x86-vsyscall-64-Warn-and-fail-vsyscall-emulation-in-.patch

From e8354b2be6f97e97515021452082436cec8857ea Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <[email protected]>
Date: Sun, 10 Dec 2017 22:47:20 -0800
Subject: [PATCH 167/232] x86/vsyscall/64: Warn and fail vsyscall emulation in
 NATIVE mode
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CVE-2017-5754

If something goes wrong with pagetable setup, vsyscall=native will
accidentally fall back to emulation.  Make it warn and fail so that we
notice.

Signed-off-by: Andy Lutomirski <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Laight <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
(cherry picked from commit 4831b779403a836158917d59a7ca880483c67378)
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Kleber Sacilotto de Souza <[email protected]>
(cherry picked from commit ba10c7488b12c3106d79c8b2ba3f4e79c7e40ee4)
Signed-off-by: Fabian Grünbichler <[email protected]>
---
 arch/x86/entry/vsyscall/vsyscall_64.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 91f3133cf5f1..5e56a4ced848 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -138,6 +138,10 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
 
 	WARN_ON_ONCE(address != regs->ip);
 
+	/* This should be unreachable in NATIVE mode. */
+	if (WARN_ON(vsyscall_mode == NATIVE))
+		return false;
+
 	if (vsyscall_mode == NONE) {
 		warn_bad_vsyscall(KERN_INFO, regs,
 				  "vsyscall attempted with vsyscall=none");
-- 
2.14.2