From: Andy Lutomirski <luto@amacapital.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Brian Gerst <brgerst@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Borislav Petkov <bp@alien8.de>, Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Josh Poimboeuf <jpoimboe@redhat.com>, Jann Horn <jann@thejh.net>,
Heiko Carstens <heiko.carstens@de.ibm.com>
Subject: Re: [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks
Date: Mon, 27 Jun 2016 10:30:31 -0700 [thread overview]
Message-ID: <CALCETrW9aeSMq7b9OaxnN6zJBnhEDtQ85Q4UC2eoft5v59FvBw@mail.gmail.com> (raw)
In-Reply-To: <CA+55aFznPpS8rT_GLdAyHsr80B2FCb2Hm-4b9QTqREMCv6_s-Q@mail.gmail.com>
On Mon, Jun 27, 2016 at 10:28 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> On Mon, Jun 27, 2016 at 8:54 AM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> How about:
>>
>> tsk_stack = (unsigned long)task_stack_page(tsk);
>> if (regs->rsp <= tsk_stack + 7*8 && regs->rsp > tsk_stack - PAGE_SIZE) {
>
> I'm not at all convinced that regs->rsp will be all that reliable
> under a double-fault scenario either. I'd be more inclined to trusr
> cr2 than the register state.
>
> It's true that double faults can happen for *other* reasons entirely,
> and as such it's not clear that %cr2 is reliable either, but since
> this is all just about a printout, I'd rather go that way anyway.
Fair enough. The chance that we get #GP-in-#GP or similar while CR2
coincidentally points to the guard page is quite low. I'll add all
the details to the comment but I'll leave the code alone.
FWIW, the manual only says that CS and RIP are untrustworthy, not that
RSP is untrustworthy, but it doesn't specify *what* RSP would contain
anywhere I can find. I don't think this is important enough to start
harassing the Intel and AMD folks over.
--Andy
next prev parent reply other threads:[~2016-06-27 17:30 UTC|newest]
Thread overview: 136+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-26 21:55 [PATCH v4 00/29] virtually mapped stacks and thread_info cleanup Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 01/29] bluetooth: Switch SMP to crypto_cipher_encrypt_one() Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
[not found] ` <264af59a3060c2bc2a725cfc66a8fa68219d1c4a.1466974736.git.luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-06-27 5:58 ` Marcel Holtmann
2016-06-27 5:58 ` Marcel Holtmann
2016-06-27 8:54 ` Ingo Molnar
2016-06-27 8:54 ` Ingo Molnar
2016-06-27 22:30 ` Marcel Holtmann
2016-06-27 22:30 ` Marcel Holtmann
2016-06-27 22:33 ` Andy Lutomirski
2016-07-04 17:56 ` Marcel Holtmann
2016-07-04 17:56 ` Marcel Holtmann
2016-07-06 13:17 ` Andy Lutomirski
2016-07-06 13:17 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 03/29] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 04/29] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski
2016-06-28 18:48 ` Borislav Petkov
2016-06-28 19:07 ` Andy Lutomirski
2016-06-28 19:07 ` Andy Lutomirski
[not found] ` <cover.1466974736.git.luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
2016-06-26 21:55 ` [PATCH v4 05/29] x86/mm: Remove kernel_unmap_pages_in_pgd() and efi_cleanup_page_tables() Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-27 7:19 ` Borislav Petkov
2016-06-27 7:19 ` Borislav Petkov
2016-06-26 21:55 ` [PATCH v4 06/29] mm: Track NR_KERNEL_STACK in KiB instead of number of stacks Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 07/29] mm: Fix memcg stack accounting for sub-page stacks Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 08/29] dma-api: Teach the "DMA-from-stack" check about vmapped stacks Andy Lutomirski
2016-06-30 19:37 ` Borislav Petkov
2016-06-30 19:37 ` Borislav Petkov
2016-07-06 13:20 ` Andy Lutomirski
2016-07-06 13:20 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 09/29] fork: Add generic vmalloced stack support Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-07-01 14:59 ` Borislav Petkov
2016-07-01 14:59 ` Borislav Petkov
2016-07-01 16:30 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 10/29] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-07-02 17:24 ` Borislav Petkov
2016-07-02 17:24 ` Borislav Petkov
2016-07-02 18:34 ` Josh Poimboeuf
2016-07-03 9:40 ` Borislav Petkov
2016-07-03 14:25 ` Andy Lutomirski
2016-07-03 14:25 ` Andy Lutomirski
2016-07-03 18:42 ` Borislav Petkov
2016-06-26 21:55 ` [PATCH v4 11/29] x86/dumpstack: When OOPSing, rewind the stack before do_exit Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-07-04 18:45 ` Borislav Petkov
2016-06-26 21:55 ` [PATCH v4 12/29] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 13/29] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 14/29] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 15/29] x86/mm/64: Enable vmapped stacks Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-27 15:01 ` Brian Gerst
2016-06-27 15:01 ` Brian Gerst
2016-06-27 15:12 ` Brian Gerst
2016-06-27 15:22 ` Andy Lutomirski
2016-06-27 15:22 ` Andy Lutomirski
2016-06-27 15:54 ` Andy Lutomirski
2016-06-27 15:54 ` Andy Lutomirski
2016-06-27 16:17 ` Brian Gerst
2016-06-27 16:17 ` Brian Gerst
2016-06-27 16:35 ` Andy Lutomirski
2016-06-27 16:35 ` Andy Lutomirski
2016-06-27 17:09 ` Brian Gerst
2016-06-27 17:23 ` Brian Gerst
2016-06-27 17:28 ` Linus Torvalds
2016-06-27 17:30 ` Andy Lutomirski [this message]
2016-06-26 21:55 ` [PATCH v4 16/29] x86/mm: Improve stack-overflow #PF handling Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 17/29] x86: Move uaccess_err and sig_on_uaccess_err to thread_struct Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 18/29] x86: Move addr_limit " Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 19/29] signal: Consolidate {TS,TLF}_RESTORE_SIGMASK code Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 20/29] x86/smp: Remove stack_smp_processor_id() Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 21/29] x86/smp: Remove unnecessary initialization of thread_info::cpu Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 22/29] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 23:55 ` Brian Gerst
2016-06-27 0:23 ` Andy Lutomirski
2016-06-27 0:36 ` Brian Gerst
2016-06-27 0:40 ` Andy Lutomirski
2016-06-27 0:40 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 23/29] kdb: Use task_cpu() instead of task_thread_info()->cpu Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 24/29] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 25/29] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 23:40 ` Brian Gerst
2016-06-26 23:49 ` Andy Lutomirski
2016-06-26 23:49 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 26/29] sched: Allow putting thread_info into task_struct Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-07-11 10:08 ` [kernel-hardening] " Mark Rutland
2016-07-11 14:55 ` Andy Lutomirski
2016-07-11 14:55 ` Andy Lutomirski
2016-07-11 15:08 ` Mark Rutland
2016-07-11 16:06 ` Linus Torvalds
2016-07-11 16:31 ` [kernel-hardening] " Mark Rutland
2016-07-11 16:31 ` Mark Rutland
2016-07-11 16:42 ` Linus Torvalds
2016-06-26 21:55 ` [PATCH v4 27/29] x86: Move " Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 28/29] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski
2016-06-26 21:55 ` Andy Lutomirski
2016-06-27 2:35 ` Andy Lutomirski
2016-06-26 21:55 ` [PATCH v4 29/29] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski
2016-06-28 7:32 ` [PATCH v4 02/29] rxrpc: Avoid using stack memory in SG lists in rxkad David Howells
2016-06-28 7:37 ` Herbert Xu
2016-06-28 9:07 ` David Howells
2016-06-28 9:45 ` Herbert Xu
2016-06-28 9:45 ` Herbert Xu
2016-06-28 7:41 ` David Howells
2016-06-28 7:41 ` David Howells
2016-06-28 7:52 ` David Howells
2016-06-28 7:55 ` Herbert Xu
2016-06-28 8:54 ` David Howells
2016-06-28 9:43 ` Herbert Xu
2016-06-28 9:43 ` Herbert Xu
2016-06-28 10:00 ` David Howells
2016-06-28 10:00 ` David Howells
2016-06-28 13:23 ` David Howells
2016-06-29 7:06 ` [PATCH v4 00/29] virtually mapped stacks and thread_info cleanup Mika Penttilä
2016-06-29 7:06 ` Mika Penttilä
2016-06-29 17:24 ` Mika Penttilä
2016-06-29 17:24 ` Mika Penttilä
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