From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
<x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Cc: Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>
Subject: [PATCH 1/2] x86/kasan: clear kasan_zero_page after TLB flush
Date: Mon, 11 Jan 2016 15:51:18 +0300 [thread overview]
Message-ID: <1452516679-32040-2-git-send-email-aryabinin@virtuozzo.com> (raw)
In-Reply-To: <1452516679-32040-1-git-send-email-aryabinin@virtuozzo.com>
Currently we clear kasan_zero_page before __flush_tlb_all(). This
works with current implementation of native_flush_tlb[_global]()
because it doesn't cause do any writes to kasan shadow memory.
But any subtle change made in native_flush_tlb*() could break this.
Also current code seems doesn't work for paravirt guests (lguest).
Only after the TLB flush we can be sure that kasan_zero_page is not
used as early shadow anymore (instrumented code will not write to it).
So it should cleared it only after the TLB flush.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
arch/x86/mm/kasan_init_64.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index d470cf2..303e470 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -120,11 +120,16 @@ void __init kasan_init(void)
kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
(void *)KASAN_SHADOW_END);
- memset(kasan_zero_page, 0, PAGE_SIZE);
-
load_cr3(init_level4_pgt);
__flush_tlb_all();
- init_task.kasan_depth = 0;
+ /*
+ * 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.
+ */
+ memset(kasan_zero_page, 0, PAGE_SIZE);
+
+ init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
}
--
2.4.10
next prev parent reply other threads:[~2016-01-11 12:50 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-08 23:15 [RFC 00/13] x86/mm: PCID and INVPCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 01/13] x86/paravirt: Turn KASAN off for parvirt.o Andy Lutomirski
2016-01-10 18:59 ` Borislav Petkov
2016-01-11 12:51 ` Andrey Ryabinin
2016-01-11 12:51 ` Andrey Ryabinin [this message]
2016-01-18 22:24 ` [PATCH 1/2] x86/kasan: clear kasan_zero_page after TLB flush Andy Lutomirski
2016-02-09 16:06 ` [tip:x86/mm] x86/kasan: Clear " tip-bot for Andrey Ryabinin
2016-01-11 12:51 ` [PATCH 2/2] x86/kasan: write protect kasan zero shadow Andrey Ryabinin
2016-01-18 22:24 ` Andy Lutomirski
2016-02-09 16:07 ` [tip:x86/mm] x86/kasan: Write " tip-bot for Andrey Ryabinin
2016-01-29 10:35 ` [RFC 01/13] x86/paravirt: Turn KASAN off for parvirt.o Borislav Petkov
2016-01-08 23:15 ` [RFC 02/13] x86/mm: Add INVPCID helpers Andy Lutomirski
2016-01-08 23:15 ` [RFC 03/13] x86/mm: Add a noinvpcid option to turn off INVPCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 04/13] x86/mm: If INVPCID is available, use it to flush global mappings Andy Lutomirski
2016-01-08 23:15 ` [RFC 05/13] x86/mm: Add barriers and document switch_mm-vs-flush synchronization Andy Lutomirski
2016-06-03 17:42 ` Nadav Amit
2016-06-09 17:24 ` Andy Lutomirski
2016-06-09 19:45 ` Nadav Amit
2016-09-06 1:22 ` Wanpeng Li
2016-01-08 23:15 ` [RFC 06/13] x86/mm: Disable PCID on 32-bit kernels Andy Lutomirski
2016-01-08 23:15 ` [RFC 07/13] x86/mm: Add nopcid to turn off PCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 08/13] x86/mm: Teach CR3 readers about PCID Andy Lutomirski
2016-01-08 23:15 ` [RFC 09/13] x86/mm: Disable interrupts when flushing the TLB using CR3 Andy Lutomirski
2016-01-08 23:41 ` Linus Torvalds
2016-01-09 0:18 ` Andy Lutomirski
2016-01-09 2:20 ` Linus Torvalds
2016-01-11 10:51 ` Ingo Molnar
2016-01-13 23:32 ` Andy Lutomirski
2016-01-13 23:35 ` Andy Lutomirski
2016-01-13 23:43 ` Dave Hansen
2016-01-13 23:51 ` Andy Lutomirski
2016-01-13 23:56 ` Dave Hansen
2016-01-14 0:34 ` Andy Lutomirski
2016-01-08 23:15 ` [RFC 10/13] x86/mm: Factor out remote TLB flushing Andy Lutomirski
2016-01-08 23:15 ` [RFC 11/13] x86/mm: Build arch/x86/mm/tlb.c even on !SMP Andy Lutomirski
2016-01-08 23:55 ` Dave Hansen
2016-01-08 23:15 ` [RFC 12/13] x86/mm: Uninline switch_mm Andy Lutomirski
2016-01-08 23:15 ` [RFC 13/13] x86/mm: Try to preserve old TLB entries using PCID Andy Lutomirski
2016-01-09 0:27 ` Dave Hansen
2016-01-09 2:19 ` Andy Lutomirski
2016-01-08 23:31 ` [RFC 00/13] x86/mm: PCID and INVPCID Linus Torvalds
2016-01-08 23:36 ` Andy Lutomirski
2016-01-08 23:42 ` Linus Torvalds
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