lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 23 Sep 2021 19:13:06 -0700
From:   Andrew Morton <>
To:     Kees Cook <>
Cc:     Thomas Gleixner <>,
        Josh Poimboeuf <>,
        Vito Caputo <>,
        Ingo Molnar <>, Borislav Petkov <>,
        "H. Peter Anvin" <>, Jens Axboe <>,
        Mark Rutland <>,
        Peter Zijlstra <>,
        Stefan Metzmacher <>,
        Andy Lutomirski <>,
        Lai Jiangshan <>,
        Christian Brauner <>,
        "" <>,
        Daniel Bristot de Oliveira <>,
        Michael WeiƟ 
        Anand K Mistry <>,
        Alexey Gladkov <>,
        Michal Hocko <>, Helge Deller <>,
        Dave Hansen <>,
        Andrea Righi <>,
        Ohhoon Kwon <>,
        Kalesh Singh <>,
        YiFei Zhu <>,
        "Eric W. Biederman" <>,,,,
Subject: Re: [PATCH] proc: Disable /proc/$pid/wchan

On Thu, 23 Sep 2021 16:31:05 -0700 Kees Cook <> 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.

Powered by blists - more mailing lists