From: Andrew Morton <akpm@linux-foundation.org>
To: Kees Cook <keescook@chromium.org>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
"Josh Poimboeuf" <jpoimboe@redhat.com>,
"Vito Caputo" <vcaputo@pengaru.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, "Jens Axboe" <axboe@kernel.dk>,
"Mark Rutland" <mark.rutland@arm.com>,
"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>,
"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>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-fsdevel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] proc: Disable /proc/$pid/wchan
Date: Thu, 23 Sep 2021 19:13:06 -0700 [thread overview]
Message-ID: <20210923191306.664d39866761778a4a6ea56c@linux-foundation.org> (raw)
In-Reply-To: <20210923233105.4045080-1-keescook@chromium.org>
On Thu, 23 Sep 2021 16:31:05 -0700 Kees Cook <keescook@chromium.org> wrote:
> The /proc/$pid/wchan file has been broken by default on x86_64 for 4
> years now[1].
[1] is hard to decrypt. I think it would be better if this changelog
were to describe the problem directly, completely and succinctly?
> As this remains a potential leak of either kernel
> addresses (when symbolization fails) or limited observation of kernel
> function progress, just remove the contents for good.
>
> Unconditionally set the contents to "0" and also mark the wchan
> field in /proc/$pid/stat with 0.
>
> This leaves kernel/sched/fair.c as the only user of get_wchan(). But
> again, since this was broken for 4 years, was this profiling logic
> actually doing anything useful?
Agree that returning a hard-wired "0\n" is the way to go.
next prev parent reply other threads:[~2021-09-24 2:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 23:31 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
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 [this message]
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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