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From: Kees Cook <keescook@chromium.org>
To: Christopher Lameter <cl@linux.com>
Cc: Alexander Popov <alex.popov@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>,
	Linux-MM <linux-mm@kvack.org>, Tycho Andersen <tycho@docker.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kernel-hardening@lists.openwall.com" 
	<kernel-hardening@lists.openwall.com>
Subject: Re: [v3] mm: Add SLUB free list pointer obfuscation
Date: Wed, 26 Jul 2017 10:13:59 -0700	[thread overview]
Message-ID: <CAGXu5jLNeO-WmaQXp9z-+iw2sha-DXixtQ-fjQmahUkh0Hvxeg@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1707261154140.9167@nuc-kabylake>

On Wed, Jul 26, 2017 at 9:55 AM, Christopher Lameter <cl@linux.com> wrote:
> On Wed, 26 Jul 2017, Kees Cook wrote:
>
>> >> What happens if, instead of BUG_ON, we do:
>> >>
>> >> if (unlikely(WARN_RATELIMIT(object == fp, "double-free detected"))
>> >>         return;
>> >
>> > This may work for the free fastpath but the set_freepointer function is
>> > use in multiple other locations. Maybe just add this to the fastpath
>> > instead of to this fucnction?
>>
>> Do you mean do_slab_free()?
>
> Yes inserting these lines into do_slab_free() would simple ignore the
> double free operation in the fast path and that would be safe.
>
> Although in either case we are adding code to the fastpath...

While I'd like it unconditionally, I think Alexander's proposal was to
put it behind CONFIG_SLAB_FREELIST_HARDENED.

BTW, while I've got your attention, can you Ack the other patch? I
sent a v4 for the pointer obfuscation, which we really need:
https://lkml.org/lkml/2017/7/26/4

Thanks!

-Kees

-- 
Kees Cook
Pixel Security

WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Christopher Lameter <cl@linux.com>
Cc: Alexander Popov <alex.popov@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>,
	Linux-MM <linux-mm@kvack.org>, Tycho Andersen <tycho@docker.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>
Subject: Re: [v3] mm: Add SLUB free list pointer obfuscation
Date: Wed, 26 Jul 2017 10:13:59 -0700	[thread overview]
Message-ID: <CAGXu5jLNeO-WmaQXp9z-+iw2sha-DXixtQ-fjQmahUkh0Hvxeg@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1707261154140.9167@nuc-kabylake>

On Wed, Jul 26, 2017 at 9:55 AM, Christopher Lameter <cl@linux.com> wrote:
> On Wed, 26 Jul 2017, Kees Cook wrote:
>
>> >> What happens if, instead of BUG_ON, we do:
>> >>
>> >> if (unlikely(WARN_RATELIMIT(object == fp, "double-free detected"))
>> >>         return;
>> >
>> > This may work for the free fastpath but the set_freepointer function is
>> > use in multiple other locations. Maybe just add this to the fastpath
>> > instead of to this fucnction?
>>
>> Do you mean do_slab_free()?
>
> Yes inserting these lines into do_slab_free() would simple ignore the
> double free operation in the fast path and that would be safe.
>
> Although in either case we are adding code to the fastpath...

While I'd like it unconditionally, I think Alexander's proposal was to
put it behind CONFIG_SLAB_FREELIST_HARDENED.

BTW, while I've got your attention, can you Ack the other patch? I
sent a v4 for the pointer obfuscation, which we really need:
https://lkml.org/lkml/2017/7/26/4

Thanks!

-Kees

-- 
Kees Cook
Pixel Security

--
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WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Christopher Lameter <cl@linux.com>
Cc: Alexander Popov <alex.popov@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Andy Lutomirski <luto@kernel.org>,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	Tejun Heo <tj@kernel.org>, Daniel Mack <daniel@zonque.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Helge Deller <deller@gmx.de>, Rik van Riel <riel@redhat.com>,
	Linux-MM <linux-mm@kvack.org>, Tycho Andersen <tycho@docker.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>
Subject: [kernel-hardening] Re: [v3] mm: Add SLUB free list pointer obfuscation
Date: Wed, 26 Jul 2017 10:13:59 -0700	[thread overview]
Message-ID: <CAGXu5jLNeO-WmaQXp9z-+iw2sha-DXixtQ-fjQmahUkh0Hvxeg@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1707261154140.9167@nuc-kabylake>

On Wed, Jul 26, 2017 at 9:55 AM, Christopher Lameter <cl@linux.com> wrote:
> On Wed, 26 Jul 2017, Kees Cook wrote:
>
>> >> What happens if, instead of BUG_ON, we do:
>> >>
>> >> if (unlikely(WARN_RATELIMIT(object == fp, "double-free detected"))
>> >>         return;
>> >
>> > This may work for the free fastpath but the set_freepointer function is
>> > use in multiple other locations. Maybe just add this to the fastpath
>> > instead of to this fucnction?
>>
>> Do you mean do_slab_free()?
>
> Yes inserting these lines into do_slab_free() would simple ignore the
> double free operation in the fast path and that would be safe.
>
> Although in either case we are adding code to the fastpath...

While I'd like it unconditionally, I think Alexander's proposal was to
put it behind CONFIG_SLAB_FREELIST_HARDENED.

BTW, while I've got your attention, can you Ack the other patch? I
sent a v4 for the pointer obfuscation, which we really need:
https://lkml.org/lkml/2017/7/26/4

Thanks!

-Kees

-- 
Kees Cook
Pixel Security

  reply	other threads:[~2017-07-26 17:14 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-06  0:27 [PATCH v3] mm: Add SLUB free list pointer obfuscation Kees Cook
2017-07-06  0:27 ` [kernel-hardening] " Kees Cook
2017-07-06  0:27 ` Kees Cook
2017-07-06 13:43 ` Christoph Lameter
2017-07-06 13:43   ` [kernel-hardening] " Christoph Lameter
2017-07-06 13:43   ` Christoph Lameter
2017-07-06 15:48   ` Kees Cook
2017-07-06 15:48     ` [kernel-hardening] " Kees Cook
2017-07-06 15:48     ` Kees Cook
2017-07-06 15:55     ` Christoph Lameter
2017-07-06 15:55       ` [kernel-hardening] " Christoph Lameter
2017-07-06 15:55       ` Christoph Lameter
2017-07-06 16:16       ` [kernel-hardening] " Daniel Micay
2017-07-06 16:16         ` Daniel Micay
2017-07-06 16:16         ` Daniel Micay
2017-07-06 17:53       ` Rik van Riel
2017-07-06 17:53         ` [kernel-hardening] " Rik van Riel
2017-07-06 17:53         ` Rik van Riel
2017-07-06 18:50         ` Kees Cook
2017-07-06 18:50           ` [kernel-hardening] " Kees Cook
2017-07-06 18:50           ` Kees Cook
2017-07-07 13:50           ` Christoph Lameter
2017-07-07 13:50             ` [kernel-hardening] " Christoph Lameter
2017-07-07 13:50             ` Christoph Lameter
2017-07-07 16:51             ` Kees Cook
2017-07-07 16:51               ` [kernel-hardening] " Kees Cook
2017-07-07 16:51               ` Kees Cook
2017-07-07 17:06               ` Christoph Lameter
2017-07-07 17:06                 ` [kernel-hardening] " Christoph Lameter
2017-07-07 17:06                 ` Christoph Lameter
2017-07-07 18:43                 ` Kees Cook
2017-07-07 18:43                   ` [kernel-hardening] " Kees Cook
2017-07-07 18:43                   ` Kees Cook
2017-07-24 21:17 ` [v3] " Alexander Popov
2017-07-24 21:17   ` [kernel-hardening] " Alexander Popov
2017-07-24 21:17   ` Alexander Popov
2017-07-25  9:42   ` Alexander Popov
2017-07-25  9:42     ` [kernel-hardening] " Alexander Popov
2017-07-25  9:42     ` Alexander Popov
2017-07-26  0:21   ` Kees Cook
2017-07-26  0:21     ` [kernel-hardening] " Kees Cook
2017-07-26  0:21     ` Kees Cook
2017-07-26 14:08     ` Christopher Lameter
2017-07-26 14:08       ` [kernel-hardening] " Christopher Lameter
2017-07-26 14:08       ` Christopher Lameter
2017-07-26 16:20       ` Kees Cook
2017-07-26 16:20         ` [kernel-hardening] " Kees Cook
2017-07-26 16:20         ` Kees Cook
2017-07-26 16:55         ` Christopher Lameter
2017-07-26 16:55           ` [kernel-hardening] " Christopher Lameter
2017-07-26 16:55           ` Christopher Lameter
2017-07-26 17:13           ` Kees Cook [this message]
2017-07-26 17:13             ` [kernel-hardening] " Kees Cook
2017-07-26 17:13             ` Kees Cook
2017-07-27 15:15             ` Christopher Lameter
2017-07-27 15:15               ` [kernel-hardening] " Christopher Lameter
2017-07-27 15:15               ` Christopher Lameter
2017-07-27 22:48           ` Alexander Popov
2017-07-27 22:48             ` [kernel-hardening] " Alexander Popov
2017-07-27 22:48             ` Alexander Popov
2017-07-27 23:53             ` Christopher Lameter
2017-07-27 23:53               ` [kernel-hardening] " Christopher Lameter
2017-07-27 23:53               ` Christopher Lameter
2017-07-31 20:17               ` Alexander Popov
2017-07-31 20:17                 ` [kernel-hardening] " Alexander Popov
2017-07-31 20:17                 ` Alexander Popov

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