From: Kees Cook <keescook@chromium.org>
To: Mark Brown <broonie@kernel.org>
Cc: "Josh Poimboeuf" <jpoimboe@redhat.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Vito Caputo" <vcaputo@pengaru.com>,
"Jann Horn" <jannh@google.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, "Jens Axboe" <axboe@kernel.dk>,
"Peter Zijlstra" <peterz@infradead.org>,
"Stefan Metzmacher" <metze@samba.org>,
"Andy Lutomirski" <luto@kernel.org>,
"Lai Jiangshan" <laijs@linux.alibaba.com>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Kenta.Tada@sony.com" <Kenta.Tada@sony.com>,
"Daniel Bristot de Oliveira" <bristot@redhat.com>,
"Michael Weiß" <michael.weiss@aisec.fraunhofer.de>,
"Anand K Mistry" <amistry@google.com>,
"Alexey Gladkov" <legion@kernel.org>,
"Michal Hocko" <mhocko@suse.com>, "Helge Deller" <deller@gmx.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Andrea Righi" <andrea.righi@canonical.com>,
"Ohhoon Kwon" <ohoono.kwon@samsung.com>,
"Kalesh Singh" <kaleshsingh@google.com>,
"YiFei Zhu" <yifeifz2@illinois.edu>,
"Eric W. Biederman" <ebiederm@xmission.com>,
"Qi Zheng" <zhengqi.arch@bytedance.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] proc: Disable /proc/$pid/wchan
Date: Wed, 29 Sep 2021 12:26:30 -0700 [thread overview]
Message-ID: <202109291224.8C538667@keescook> (raw)
In-Reply-To: <20210929190042.GU4199@sirena.org.uk>
On Wed, Sep 29, 2021 at 08:00:42PM +0100, Mark Brown wrote:
> On Wed, Sep 29, 2021 at 11:54:55AM -0700, Kees Cook wrote:
> > On Mon, Sep 27, 2021 at 01:50:56PM -0700, Josh Poimboeuf wrote:
>
> > > Even with that patch, it doesn't lock the task's runqueue before reading
> > > the stack, so there's still the possibility of the task running on
> > > another CPU and the unwinder going off the rails a bit, which might be
> > > used by an attacker in creative ways similar to the /proc/<pid>/stack
> > > vulnerability Jann mentioned earlier.
>
> > Since I think we're considering get_wchan() to be slow-path, can we just
> > lock the runqueue and use arch_stack_walk_reliable()?
>
> Unfortunately arch_stack_walk_reliable() is only available for powerpc,
> s390 and x86 currently - work is in progress to implement it for arm64
> as well but it's not there yet.
Strictly speaking, we're only trying to fix this for x86+ORC. The other
architectures (or non-ORC x86) already have their own non-ORC unwinders
behind get_wchan(). They may have similar weaknesses (which should
certainly be fixed), I think the first step here is to restore wchan
under x86+ORC.
--
Kees Cook
next prev parent reply other threads:[~2021-09-29 19:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 23:31 [PATCH] proc: Disable /proc/$pid/wchan Kees Cook
2021-09-23 23:38 ` Kees Cook
2021-09-24 13:31 ` Peter Zijlstra
2021-09-23 23:49 ` Vito Caputo
2021-09-24 0:08 ` Jann Horn
2021-09-24 0:22 ` Vito Caputo
2021-09-24 1:16 ` Kees Cook
2021-09-24 1:34 ` Vito Caputo
2021-09-24 1:42 ` Kees Cook
2021-09-24 13:54 ` Mark Rutland
2021-09-24 14:26 ` Kees Cook
2021-09-27 9:03 ` Mark Rutland
2021-09-27 18:07 ` Kees Cook
2021-09-27 20:50 ` Josh Poimboeuf
2021-09-29 18:54 ` Kees Cook
2021-09-29 19:00 ` Mark Brown
2021-09-29 19:26 ` Kees Cook [this message]
2021-09-29 19:40 ` Peter Zijlstra
2021-09-29 21:10 ` Josh Poimboeuf
2021-09-27 9:16 ` David Laight
2021-09-29 8:48 ` Peter Zijlstra
2021-09-24 2:13 ` Andrew Morton
2021-09-24 6:04 ` Kees Cook
2021-09-24 13:29 ` Peter Zijlstra
2021-09-30 18:05 ` Stephen Brennan
2021-09-30 18:12 ` Kees Cook
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