linux-kernel - [tip:x86/boot] x86/KASLR: Initialize mapping

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Message-ID: <tip-434a6c9f90f7ab5ade619455df01ef5ebea533ee@git.kernel.org>
Date:	Tue, 10 May 2016 01:40:51 -0700
From:	tip-bot for Kees Cook <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, bhe@...hat.com, akpm@...ux-foundation.org,
	keescook@...omium.org, vgoyal@...hat.com, brgerst@...il.com,
	dyoung@...hat.com, yinghai@...nel.org, luto@...nel.org,
	luto@...capital.net, hpa@...or.com, dvlasenk@...hat.com,
	linux-kernel@...r.kernel.org, bp@...e.de, tglx@...utronix.de,
	peterz@...radead.org, torvalds@...ux-foundation.org, bp@...en8.de
Subject: [tip:x86/boot] x86/KASLR: Initialize mapping_info every time

Commit-ID:  434a6c9f90f7ab5ade619455df01ef5ebea533ee
Gitweb:     http://git.kernel.org/tip/434a6c9f90f7ab5ade619455df01ef5ebea533ee
Author:     Kees Cook <keescook@...omium.org>
AuthorDate: Mon, 9 May 2016 13:22:04 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 10 May 2016 10:12:02 +0200

x86/KASLR: Initialize mapping_info every time

As it turns out, mapping_info DOES need to be initialized every
time, because pgt_data address could be changed during kernel
relocation. So it can not be build time assigned.

Without this, page tables were not being corrected updated, which
could cause reboots when a physical address beyond 2G was chosen.

Signed-off-by: Kees Cook <keescook@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Baoquan He <bhe@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Borislav Petkov <bp@...e.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Young <dyoung@...hat.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: kernel-hardening@...ts.openwall.com
Cc: lasse.collin@...aani.org
Link: http://lkml.kernel.org/r/1462825332-10505-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/boot/compressed/pagetable.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/boot/compressed/pagetable.c b/arch/x86/boot/compressed/pagetable.c
index 3c99051..34b95df 100644
--- a/arch/x86/boot/compressed/pagetable.c
+++ b/arch/x86/boot/compressed/pagetable.c
@@ -90,23 +90,17 @@ static void prepare_level4(void)
 }
 
 /*
- * Mapping information structure passed to kernel_ident_mapping_init().
- * Since this never changes, there's no reason to repeatedly fill it
- * in on the stack when calling add_identity_map().
- */
-static struct x86_mapping_info mapping_info = {
-	.alloc_pgt_page	= alloc_pgt_page,
-	.context	= &pgt_data,
-	.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,
-};
-
-/*
  * Adds the specified range to what will become the new identity mappings.
  * Once all ranges have been added, the new mapping is activated by calling
  * finalize_identity_maps() below.
  */
 void add_identity_map(unsigned long start, unsigned long size)
 {
+	struct x86_mapping_info mapping_info = {
+		.alloc_pgt_page	= alloc_pgt_page,
+		.context	= &pgt_data,
+		.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,
+	};
 	unsigned long end = start + size;
 
 	/* Make sure we have a top level page table ready to use. */