linux-kernel - Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced threads to be reaped

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]

Message-ID: <20170403181252.GA31390@redhat.com>
Date:   Mon, 3 Apr 2017 20:12:52 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Aleksa Sarai <asarai@...e.com>,
        Andy Lutomirski <luto@...capital.net>,
        Attila Fazekas <afazekas@...hat.com>,
        Jann Horn <jann@...jh.net>, Kees Cook <keescook@...omium.org>,
        Michal Hocko <mhocko@...nel.org>,
        Ulrich Obergfell <uobergfe@...hat.com>,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [RFC][PATCH 2/2] exec: If possible don't wait for ptraced
 threads to be reaped

On 04/02, Eric W. Biederman wrote:
>
> Oleg Nesterov <oleg@...hat.com> writes:
>
> > And btw zap_other_threads(may_hang == 0) is racy. Either you need tasklist or
> > exit_notify() should set tsk->exit_state under siglock, otherwise zap() can
> > return the wrong count.
>
> zap_other_thread(tsk, 0) only gets called in the case where we don't
> care about the return value.  It does not get called from fs/exec.c

I meant that may_hang == 0 implies zap_other_threads(do_count => -1) which should
return the number of threads which didn't pass exit_notify(). The returned value
can be wrong unless you change exit_notify() to set exit_state under siglock.

Oleg.