From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Brian Gerst <brgerst@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core)
Date: Mon, 20 Jun 2016 09:07:24 +0200 [thread overview]
Message-ID: <20160620070724.GB3266@osiris> (raw)
In-Reply-To: <CALCETrUgpbTXnvkmLNZz9sSq8fgz1g8eoGv=1Lif2dhyB6GrSg@mail.gmail.com>
On Sun, Jun 19, 2016 at 11:01:48PM -0700, Andy Lutomirski wrote:
> > The tmll instruction tests if any of the higher bits within the 16k
> > stackframe address are set. In this specific case that would be bits 7-15
> > (mask 0x3f80). If no bit would be set we know that only up to 128 bytes
> > would be left on the stack, and thus trigger an exception.
> >
> > This check does of course only work if a 16k stack is also 16k aligned,
> > which is always the case.
> >
>
> Oh, interesting. How do you handle the case of a single function that
> uses more than 128 bytes of stack?
The compiler uses the next larger value of the stackframe size that is a
power of 2 for checking. So another example with a stackframe size of 472
bytes would be the below one with a mask of 0x3e00:
0000000000392db8 <htree_inlinedir_to_tree>:
392db8: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15)
392dbe: a7 f1 3e 00 tmll %r15,15872
392dc2: b9 04 00 ef lgr %r14,%r15
392dc6: a7 84 00 01 je 392dc8 <htree_inlinedir_to_tree+0x10>
392dca: e3 f0 fe 28 ff 71 lay %r15,-472(%r15)
WARNING: multiple messages have this Message-ID (diff)
From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Brian Gerst <brgerst@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [kernel-hardening] Re: [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core)
Date: Mon, 20 Jun 2016 09:07:24 +0200 [thread overview]
Message-ID: <20160620070724.GB3266@osiris> (raw)
In-Reply-To: <CALCETrUgpbTXnvkmLNZz9sSq8fgz1g8eoGv=1Lif2dhyB6GrSg@mail.gmail.com>
On Sun, Jun 19, 2016 at 11:01:48PM -0700, Andy Lutomirski wrote:
> > The tmll instruction tests if any of the higher bits within the 16k
> > stackframe address are set. In this specific case that would be bits 7-15
> > (mask 0x3f80). If no bit would be set we know that only up to 128 bytes
> > would be left on the stack, and thus trigger an exception.
> >
> > This check does of course only work if a 16k stack is also 16k aligned,
> > which is always the case.
> >
>
> Oh, interesting. How do you handle the case of a single function that
> uses more than 128 bytes of stack?
The compiler uses the next larger value of the stackframe size that is a
power of 2 for checking. So another example with a stackframe size of 472
bytes would be the below one with a mask of 0x3e00:
0000000000392db8 <htree_inlinedir_to_tree>:
392db8: eb 6f f0 48 00 24 stmg %r6,%r15,72(%r15)
392dbe: a7 f1 3e 00 tmll %r15,15872
392dc2: b9 04 00 ef lgr %r14,%r15
392dc6: a7 84 00 01 je 392dc8 <htree_inlinedir_to_tree+0x10>
392dca: e3 f0 fe 28 ff 71 lay %r15,-472(%r15)
next prev parent reply other threads:[~2016-06-20 7:35 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-16 0:28 [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 01/13] x86/mm/hotplug: Don't remove PGD entries in remove_pagetable() Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` Andy Lutomirski
2016-06-16 0:28 ` [PATCH 02/13] x86/cpa: In populate_pgd, don't set the pgd entry until it's populated Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 03/13] x86/cpa: Warn if kernel_unmap_pages_in_pgd is used inappropriately Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of number of stacks Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` Andy Lutomirski
2016-06-16 11:10 ` Vladimir Davydov
2016-06-16 11:10 ` [kernel-hardening] " Vladimir Davydov
2016-06-16 11:10 ` Vladimir Davydov
2016-06-16 17:21 ` Andy Lutomirski
2016-06-16 17:21 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 17:21 ` Andy Lutomirski
2016-06-16 19:20 ` Andy Lutomirski
2016-06-16 19:20 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 19:20 ` Andy Lutomirski
2016-06-16 15:33 ` Josh Poimboeuf
2016-06-16 15:33 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 15:33 ` Josh Poimboeuf
2016-06-16 17:39 ` Andy Lutomirski
2016-06-16 17:39 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 17:39 ` Andy Lutomirski
2016-06-16 19:39 ` Josh Poimboeuf
2016-06-16 19:39 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 19:39 ` Josh Poimboeuf
2016-06-16 0:28 ` [PATCH 05/13] mm: Move memcg stack accounting to account_kernel_stack Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` Andy Lutomirski
2016-06-16 0:28 ` [PATCH 06/13] fork: Add generic vmalloced stack support Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 17:25 ` Kees Cook
2016-06-16 17:25 ` [kernel-hardening] " Kees Cook
2016-06-16 17:37 ` Andy Lutomirski
2016-06-16 17:37 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 07/13] x86/die: Don't try to recover from an OOPS on a non-default stack Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 08/13] x86/dumpstack: When OOPSing, rewind the stack before do_exit Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 17:50 ` Josh Poimboeuf
2016-06-16 17:50 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 17:57 ` Andy Lutomirski
2016-06-16 17:57 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 09/13] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 11:56 ` Borislav Petkov
2016-06-16 11:56 ` [kernel-hardening] " Borislav Petkov
2016-07-08 12:07 ` [tip:x86/debug] x86/dumpstack: Honor supplied @regs arg tip-bot for Andy Lutomirski
2016-06-16 0:28 ` [PATCH 10/13] x86/dumpstack: Try harder to get a call trace on stack overflow Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 18:16 ` Josh Poimboeuf
2016-06-16 18:16 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 18:22 ` Andy Lutomirski
2016-06-16 18:22 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 18:33 ` Josh Poimboeuf
2016-06-16 18:33 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 18:37 ` Andy Lutomirski
2016-06-16 18:37 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 18:54 ` Josh Poimboeuf
2016-06-16 18:54 ` [kernel-hardening] " Josh Poimboeuf
2016-06-16 0:28 ` [PATCH 11/13] x86/dumpstack/64: Handle faults when printing the "Stack:" part of an OOPS Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 0:28 ` [PATCH 12/13] x86/mm/64: Enable vmapped stacks Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 4:17 ` Mika Penttilä
2016-06-16 4:17 ` [kernel-hardening] " Mika Penttilä
2016-06-16 5:33 ` Andy Lutomirski
2016-06-16 5:33 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 13:11 ` Rik van Riel
2016-06-16 0:28 ` [PATCH 13/13] x86/mm: Improve stack-overflow #PF handling Andy Lutomirski
2016-06-16 0:28 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 6:05 ` [PATCH 00/13] Virtually mapped stacks with guard pages (x86, core) Heiko Carstens
2016-06-16 6:05 ` [kernel-hardening] " Heiko Carstens
2016-06-16 17:50 ` Andy Lutomirski
2016-06-16 17:50 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 18:14 ` Andy Lutomirski
2016-06-16 18:14 ` [kernel-hardening] " Andy Lutomirski
2016-06-16 21:27 ` Andy Lutomirski
2016-06-16 21:27 ` [kernel-hardening] " Andy Lutomirski
2016-06-17 3:58 ` Andy Lutomirski
2016-06-17 3:58 ` [kernel-hardening] " Andy Lutomirski
2016-06-17 7:27 ` Heiko Carstens
2016-06-17 7:27 ` [kernel-hardening] " Heiko Carstens
2016-06-17 17:38 ` Andy Lutomirski
2016-06-17 17:38 ` [kernel-hardening] " Andy Lutomirski
2016-06-20 5:58 ` Heiko Carstens
2016-06-20 5:58 ` [kernel-hardening] " Heiko Carstens
2016-06-20 6:01 ` Andy Lutomirski
2016-06-20 6:01 ` [kernel-hardening] " Andy Lutomirski
2016-06-20 7:07 ` Heiko Carstens [this message]
2016-06-20 7:07 ` Heiko Carstens
2016-06-16 17:24 ` Kees Cook
2016-06-16 17:24 ` [kernel-hardening] " Kees Cook
2016-07-04 22:31 [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message Borislav Petkov
2016-07-04 22:31 ` [PATCH -v2 1/3] x86/dumpstack: Honor supplied @regs arg Borislav Petkov
2016-07-04 22:31 ` [PATCH -v2 2/3] printk: Make the printk*once() variants return a value Borislav Petkov
2016-07-08 12:08 ` [tip:x86/debug] " tip-bot for Borislav Petkov
2016-07-09 2:40 ` Joe Perches
2016-07-09 7:50 ` Borislav Petkov
2016-07-09 17:56 ` Joe Perches
2016-07-10 6:49 ` Borislav Petkov
2016-07-10 8:23 ` Joe Perches
2016-07-10 12:06 ` Borislav Petkov
2016-07-10 12:33 ` Joe Perches
2016-07-04 22:31 ` [PATCH -v2 3/3] x86/dumpstack: Add show_stack_regs() and use it Borislav Petkov
2016-07-08 12:08 ` [tip:x86/debug] " tip-bot for Borislav Petkov
2016-07-06 12:58 ` [PATCH -v2 0/3] x86/MSR: Improve unhandled MSR access error message Andy Lutomirski
2016-07-06 13:11 ` Borislav Petkov
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