linux-kernel - [tip:x86/mm] x86/kasan: Write protect kasan zero shadow

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-063fb3e56f6dd29b2633b678b837e1d904200e6f@git.kernel.org>
Date:	Tue, 9 Feb 2016 08:07:10 -0800
From:	tip-bot for Andrey Ryabinin <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	bp@...e.de, torvalds@...ux-foundation.org, toshi.kani@...com,
	dave.hansen@...ux.intel.com, bp@...en8.de, mcgrof@...e.com,
	dvlasenk@...hat.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, luto@...nel.org,
	aryabinin@...tuozzo.com, oleg@...hat.com, peterz@...radead.org,
	hpa@...or.com, brgerst@...il.com, luto@...capital.net,
	mingo@...nel.org, tglx@...utronix.de
Subject: [tip:x86/mm] x86/kasan: Write protect kasan zero shadow

Commit-ID:  063fb3e56f6dd29b2633b678b837e1d904200e6f
Gitweb:     http://git.kernel.org/tip/063fb3e56f6dd29b2633b678b837e1d904200e6f
Author:     Andrey Ryabinin <aryabinin@...tuozzo.com>
AuthorDate: Mon, 11 Jan 2016 15:51:19 +0300
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 9 Feb 2016 13:33:14 +0100

x86/kasan: Write protect kasan zero shadow

After kasan_init() executed, no one is allowed to write to kasan_zero_page,
so write protect it.

Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
Reviewed-by: Borislav Petkov <bp@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@...e.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Toshi Kani <toshi.kani@...com>
Cc: linux-mm@...ck.org
Link: http://lkml.kernel.org/r/1452516679-32040-3-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/kasan_init_64.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 303e470..1b1110f 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -125,10 +125,16 @@ void __init kasan_init(void)
 
 	/*
 	 * kasan_zero_page has been used as early shadow memory, thus it may
-	 * contain some garbage. Now we can clear it, since after the TLB flush
-	 * no one should write to it.
+	 * contain some garbage. Now we can clear and write protect it, since
+	 * after the TLB flush no one should write to it.
 	 */
 	memset(kasan_zero_page, 0, PAGE_SIZE);
+	for (i = 0; i < PTRS_PER_PTE; i++) {
+		pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
+		set_pte(&kasan_zero_pte[i], pte);
+	}
+	/* Flush TLBs again to be sure that write protection applied. */
+	__flush_tlb_all();
 
 	init_task.kasan_depth = 0;
 	pr_info("KernelAddressSanitizer initialized\n");