oss-security - Re: [PATCH 1/2] oom: don't ignore rss in nascent mm

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Date: Fri, 10 Sep 2010 02:39:58 -0700 (PDT)
From: Roland McGrath <roland@...hat.com>
To: Oleg Nesterov <oleg@...hat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, oss-security@...ts.openwall.com,
        Solar Designer <solar@...nwall.com>,
        Kees Cook <kees.cook@...onical.com>, Al Viro <viro@...iv.linux.org.uk>,
        Neil Horman <nhorman@...driver.com>, linux-fsdevel@...r.kernel.org,
        pageexec@...email.hu, Brad Spengler <spender@...ecurity.net>,
        Eugene Teo <eugene@...hat.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH 1/2] oom: don't ignore rss in nascent mm

> I wonder if it makes sense to move ->cred_guard_mutex from task_struct
> to signal_struct and thus make multiple-threads-inside-exec impossible.
> Only one thread can win anyway.

That probably makes sense.  Note that cred_guard_mutex is also overloaded
for ptrace_attach, so this would add some more serialization of attaches to
threads in the same group.  But as long as actual attachment serializes on
tasklist_lock anyway, it doesn't make a material difference.  (Even without
that, it would presumably be the same debugger attaching serially to
threads in the same group, so it wouldn't degrade anything in practice.)

Thanks,
Roland

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