From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Andy Lutomirski <luto@kernel.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"x86@kernel.org" <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
linux-arch <linux-arch@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: KASAN vs. boot-time switching between 4- and 5-level paging
Date: Tue, 11 Jul 2017 18:15:29 +0300 [thread overview]
Message-ID: <d3caf8c4-4575-c1b5-6b0f-95527efaf2f9@virtuozzo.com> (raw)
In-Reply-To: <CALCETrVpNUq3-zEu1Q1O77N8r4kv4kFdefXp7XEs3Hpf-JPAjg@mail.gmail.com>
On 07/11/2017 06:06 PM, Andy Lutomirski wrote:
> On Tue, Jul 11, 2017 at 3:35 AM, Kirill A. Shutemov
> <kirill@shutemov.name> wrote:
>> On Mon, Jul 10, 2017 at 05:30:38PM -0700, Andy Lutomirski wrote:
>>> On Mon, Jul 10, 2017 at 2:24 PM, Kirill A. Shutemov
>>> <kirill@shutemov.name> wrote:
>>>> On Mon, Jul 10, 2017 at 01:07:13PM -0700, Andy Lutomirski wrote:
>>>>> Can you give the disassembly of the backtrace lines? Blaming the
>>>>> .endr doesn't make much sense to me.
>>>>
>>>> I don't have backtrace. It's before printk() is functional. I only see
>>>> triple fault and reboot.
>>>>
>>>> I had to rely on qemu tracing and gdb.
>>>
>>> Can you ask GDB or objtool to disassemble around those addresses? Can
>>> you also attach the big dump that QEMU throws out that shows register
>>> state? In particular, CR2, CR3, and CR4 could be useful.
>>
>> The last three execptions:
>>
>> check_exception old: 0xffffffff new 0xe, cr2: 0xffffffff7ffffff8, rip: 0xffffffff84bb3036
>> RAX=00000000ffffffff RBX=ffffffff800000d8 RCX=ffffffff84be4021 RDX=dffffc0000000000
>> RSI=0000000000000006 RDI=ffffffff84c57000 RBP=ffffffff800000c8 RSP=ffffffff80000000
>
> So RSP was 0xffffffff80000000, a push happened, and we tried to write
> to 0xffffffff7ffffff8, which failed.
>
>> check_exception old: 0xe new 0xe, cr2: 0xffffffff7ffffff8, rip: 0xffffffff84bb3141
>> RAX=00000000ffffffff RBX=ffffffff800000d8 RCX=ffffffff84be4021 RDX=dffffc0000000000
>> RSI=0000000000000006 RDI=ffffffff84c57000 RBP=ffffffff800000c8 RSP=ffffffff80000000
>
> And #PF doesn't use IST, so it double-faulted.
>
> Either the stack isn't mapped in the page tables, RSP is corrupt, or
> there's a genuine stack overflow here.
>
I reproduced this, and this is kasan bug:
a??0xffffffff84864897 <x86_early_init_platform_quirks+5> mov $0xffffffff83f1d0b8,%rdi
a??0xffffffff8486489e <x86_early_init_platform_quirks+12> movabs $0xdffffc0000000000,%rax
a??0xffffffff848648a8 <x86_early_init_platform_quirks+22> push %rbp
a??0xffffffff848648a9 <x86_early_init_platform_quirks+23> mov %rdi,%rdx
a??0xffffffff848648ac <x86_early_init_platform_quirks+26> shr $0x3,%rdx
a??0xffffffff848648b0 <x86_early_init_platform_quirks+30> mov %rsp,%rbp
>a??0xffffffff848648b3 <x86_early_init_platform_quirks+33> mov (%rdx,%rax,1),%al
we crash on the last move which is a read from shadow
(gdb) p/x $rdx
$1 = 0x1ffffffff07e3a17
(gdb) p/x $rax
$2 = 0xdffffc0000000000
(gdb) p/x 0xdffffc0000000000 + 0x1ffffffff07e3a17
$4 = 0xfffffbfff07e3a17
(gdb) p/x *0xfffffbfff07e3a17
Cannot access memory at address 0xfffffbfff07e3a17
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next prev parent reply other threads:[~2017-07-11 15:13 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-25 20:33 [PATCHv1, RFC 0/8] Boot-time switching between 4- and 5-level paging Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 1/8] x86/boot/compressed/64: Detect and handle 5-level paging at boot-time Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 2/8] x86/mm: Make virtual memory layout movable for CONFIG_X86_5LEVEL Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 3/8] x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 4/8] x86/mm: Handle boot-time paging mode switching at early boot Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 5/8] x86/mm: Fold p4d page table layer at runtime Kirill A. Shutemov
2017-05-27 15:09 ` Brian Gerst
2017-05-27 22:46 ` Kirill A. Shutemov
2017-05-27 22:56 ` Brian Gerst
2017-05-25 20:33 ` [PATCHv1, RFC 6/8] x86/mm: Replace compile-time checks for 5-level with runtime-time Kirill A. Shutemov
2017-05-25 20:33 ` [PATCHv1, RFC 7/8] x86/mm: Hacks for boot-time switching between 4- and 5-level paging Kirill A. Shutemov
2017-05-26 22:10 ` KASAN vs. " Kirill A. Shutemov
2017-05-29 10:02 ` Dmitry Vyukov
2017-05-29 11:18 ` Andrey Ryabinin
2017-05-29 11:19 ` Dmitry Vyukov
2017-05-29 11:45 ` Andrey Ryabinin
2017-05-29 12:46 ` Andrey Ryabinin
2017-06-01 14:56 ` Andrey Ryabinin
2017-07-10 12:33 ` Kirill A. Shutemov
2017-07-10 12:43 ` Dmitry Vyukov
2017-07-10 14:17 ` Kirill A. Shutemov
2017-07-10 15:56 ` Andy Lutomirski
2017-07-10 18:47 ` Kirill A. Shutemov
2017-07-10 20:07 ` Andy Lutomirski
2017-07-10 21:24 ` Kirill A. Shutemov
2017-07-11 0:30 ` Andy Lutomirski
2017-07-11 10:35 ` Kirill A. Shutemov
2017-07-11 15:06 ` Andy Lutomirski
2017-07-11 15:15 ` Andrey Ryabinin [this message]
2017-07-11 16:45 ` Andrey Ryabinin
2017-07-11 17:03 ` Kirill A. Shutemov
2017-07-11 17:29 ` Andrey Ryabinin
2017-07-11 19:05 ` Kirill A. Shutemov
2017-07-13 12:58 ` Andrey Ryabinin
2017-07-13 13:52 ` Kirill A. Shutemov
2017-07-13 14:15 ` Kirill A. Shutemov
2017-07-13 14:19 ` Andrey Ryabinin
2017-07-24 12:13 ` Kirill A. Shutemov
2017-07-24 14:07 ` Andrey Ryabinin
2017-07-10 16:57 ` Andrey Ryabinin
2017-05-25 20:33 ` [PATCHv1, RFC 8/8] x86/mm: Allow to boot without la57 if CONFIG_X86_5LEVEL=y Kirill A. Shutemov
2017-05-25 23:24 ` [PATCHv1, RFC 0/8] Boot-time switching between 4- and 5-level paging Linus Torvalds
2017-05-26 0:40 ` Andy Lutomirski
2017-05-26 4:18 ` Kevin Easton
2017-05-26 7:21 ` Andy Lutomirski
2017-05-26 13:00 ` Kirill A. Shutemov
2017-05-26 13:35 ` Andi Kleen
2017-05-26 15:51 ` Linus Torvalds
2017-05-26 15:58 ` Kirill A. Shutemov
2017-05-26 16:13 ` Linus Torvalds
2017-05-26 18:24 ` hpa
2017-05-26 19:23 ` Dave Hansen
2017-05-26 19:36 ` hpa
2017-05-26 19:40 ` hpa
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