linux-kernel - Re: [PATCH] userns: suppress kmemleak message

lists.openwall.net		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, 3 Nov 2016 15:06:31 +0000
From:   Jakub Kicinski <kubakici@...pl>
To:     ebiederm@...ssion.com (Eric W. Biederman)
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Johannes Berg <johannes@...solutions.net>,
        Maciej Żenczykowski <zenczykowski@...il.com>
Subject: Re: [PATCH] userns: suppress kmemleak message

On Thu, 03 Nov 2016 09:54:25 -0500, Eric W. Biederman wrote:
> Dmitry Torokhov <dmitry.torokhov@...il.com> writes:
> 
> > We do not ever intend to unregister "user" sysctl table, unfortunately
> > it leads kmemleak to believe that we are leaking memory:  
> 
> Sounds like an issue with kmemleak because we do retain references.
> 
> So no we don't intend to unregister the table.
> 
> As for the patch.
> 
> Nacked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
> 
> I can't see the using kmemleak_not_leak is possibly good form.  I
> would much rather have suggestions about constructs that won't confuse
> kmemleak and won't need ugly annotations that serve no purpose but to
> appease a tool.  Perhaps the user_header variable needs to be moved out
> of user_namespace_sysctl_init.

FWIW the problem now is that the compiler is clever enough to never
write the pointer to memory so kmemleak can't find it.  user_header is
just held in a register for as long as it's needed even though the
variable is static.