From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Brian Gerst <brgerst@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vladimir Davydov <vdavydov@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of number of stacks
Date: Thu, 16 Jun 2016 14:39:23 -0500 [thread overview]
Message-ID: <20160616193923.hyma4vcmr7lvklcx@treble> (raw)
In-Reply-To: <CALCETrXRONH1K1zAWAFN--Lsza+5bkgtmcMrgAY_nvT-e21C3w@mail.gmail.com>
On Thu, Jun 16, 2016 at 10:39:43AM -0700, Andy Lutomirski wrote:
> On Thu, Jun 16, 2016 at 8:33 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Wed, Jun 15, 2016 at 05:28:26PM -0700, Andy Lutomirski wrote:
> >> Currently, NR_KERNEL_STACK tracks the number of kernel stacks in a
> >> zone. This only makes sense if each kernel stack exists entirely in
> >> one zone, and allowing vmapped stacks could break this assumption.
> >>
> >> It turns out that the code for tracking kernel stack allocations in
> >> units of pages is slightly simpler, so just switch to counting
> >> pages.
> >>
> >> Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
> >> Cc: Johannes Weiner <hannes@cmpxchg.org>
> >> Cc: Michal Hocko <mhocko@kernel.org>
> >> Cc: linux-mm@kvack.org
> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> ---
> >> fs/proc/meminfo.c | 2 +-
> >> kernel/fork.c | 3 ++-
> >> mm/page_alloc.c | 3 +--
> >> 3 files changed, 4 insertions(+), 4 deletions(-)
> >
> > You missed another usage of NR_KERNEL_STACK in drivers/base/node.c.
>
> Thanks.
>
> The real reason I cc'd you was so you could look at
> rewind_stack_do_exit and the sneaky trick I did in no_context in the
> last patch, though. :) Both survive objtool, but I figured I'd check
> with objtool's author as well. If there was a taint bit I could set
> saying "kernel is hosed -- don't try to apply live patches any more",
> I'd have extra confidence.
I think it all looks fine from an objtool and a live patching
standpoint. Other than my previous comment about setting the stack
pointer correctly before calling do_exit(), I didn't see anything else
which would mess up the stack of a sleeping task, which is all I really
care about.
--
Josh
WARNING: multiple messages have this Message-ID (diff)
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Brian Gerst <brgerst@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vladimir Davydov <vdavydov@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of number of stacks
Date: Thu, 16 Jun 2016 14:39:23 -0500 [thread overview]
Message-ID: <20160616193923.hyma4vcmr7lvklcx@treble> (raw)
In-Reply-To: <CALCETrXRONH1K1zAWAFN--Lsza+5bkgtmcMrgAY_nvT-e21C3w@mail.gmail.com>
On Thu, Jun 16, 2016 at 10:39:43AM -0700, Andy Lutomirski wrote:
> On Thu, Jun 16, 2016 at 8:33 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Wed, Jun 15, 2016 at 05:28:26PM -0700, Andy Lutomirski wrote:
> >> Currently, NR_KERNEL_STACK tracks the number of kernel stacks in a
> >> zone. This only makes sense if each kernel stack exists entirely in
> >> one zone, and allowing vmapped stacks could break this assumption.
> >>
> >> It turns out that the code for tracking kernel stack allocations in
> >> units of pages is slightly simpler, so just switch to counting
> >> pages.
> >>
> >> Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
> >> Cc: Johannes Weiner <hannes@cmpxchg.org>
> >> Cc: Michal Hocko <mhocko@kernel.org>
> >> Cc: linux-mm@kvack.org
> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> ---
> >> fs/proc/meminfo.c | 2 +-
> >> kernel/fork.c | 3 ++-
> >> mm/page_alloc.c | 3 +--
> >> 3 files changed, 4 insertions(+), 4 deletions(-)
> >
> > You missed another usage of NR_KERNEL_STACK in drivers/base/node.c.
>
> Thanks.
>
> The real reason I cc'd you was so you could look at
> rewind_stack_do_exit and the sneaky trick I did in no_context in the
> last patch, though. :) Both survive objtool, but I figured I'd check
> with objtool's author as well. If there was a taint bit I could set
> saying "kernel is hosed -- don't try to apply live patches any more",
> I'd have extra confidence.
I think it all looks fine from an objtool and a live patching
standpoint. Other than my previous comment about setting the stack
pointer correctly before calling do_exit(), I didn't see anything else
which would mess up the stack of a sleeping task, which is all I really
care about.
--
Josh
--
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WARNING: multiple messages have this Message-ID (diff)
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
X86 ML <x86@kernel.org>, Borislav Petkov <bp@alien8.de>,
Nadav Amit <nadav.amit@gmail.com>,
Kees Cook <keescook@chromium.org>,
Brian Gerst <brgerst@gmail.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vladimir Davydov <vdavydov@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: [kernel-hardening] Re: [PATCH 04/13] mm: Track NR_KERNEL_STACK in pages instead of number of stacks
Date: Thu, 16 Jun 2016 14:39:23 -0500 [thread overview]
Message-ID: <20160616193923.hyma4vcmr7lvklcx@treble> (raw)
In-Reply-To: <CALCETrXRONH1K1zAWAFN--Lsza+5bkgtmcMrgAY_nvT-e21C3w@mail.gmail.com>
On Thu, Jun 16, 2016 at 10:39:43AM -0700, Andy Lutomirski wrote:
> On Thu, Jun 16, 2016 at 8:33 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > On Wed, Jun 15, 2016 at 05:28:26PM -0700, Andy Lutomirski wrote:
> >> Currently, NR_KERNEL_STACK tracks the number of kernel stacks in a
> >> zone. This only makes sense if each kernel stack exists entirely in
> >> one zone, and allowing vmapped stacks could break this assumption.
> >>
> >> It turns out that the code for tracking kernel stack allocations in
> >> units of pages is slightly simpler, so just switch to counting
> >> pages.
> >>
> >> Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
> >> Cc: Johannes Weiner <hannes@cmpxchg.org>
> >> Cc: Michal Hocko <mhocko@kernel.org>
> >> Cc: linux-mm@kvack.org
> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> ---
> >> fs/proc/meminfo.c | 2 +-
> >> kernel/fork.c | 3 ++-
> >> mm/page_alloc.c | 3 +--
> >> 3 files changed, 4 insertions(+), 4 deletions(-)
> >
> > You missed another usage of NR_KERNEL_STACK in drivers/base/node.c.
>
> Thanks.
>
> The real reason I cc'd you was so you could look at
> rewind_stack_do_exit and the sneaky trick I did in no_context in the
> last patch, though. :) Both survive objtool, but I figured I'd check
> with objtool's author as well. If there was a taint bit I could set
> saying "kernel is hosed -- don't try to apply live patches any more",
> I'd have extra confidence.
I think it all looks fine from an objtool and a live patching
standpoint. Other than my previous comment about setting the stack
pointer correctly before calling do_exit(), I didn't see anything else
which would mess up the stack of a sleeping task, which is all I really
care about.
--
Josh
next prev parent reply other threads:[~2016-06-16 19:39 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 [this message]
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
2016-06-20 7:07 ` [kernel-hardening] " 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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