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Date: Mon, 29 Aug 2011 16:02:10 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Vasiliy Kulikov <segoon@openwall.com>
Cc: kernel-hardening@lists.openwall.com, Cyrill Gorcunov <gorcunov@gmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        David Rientjes <rientjes@google.com>,
        Stephen Wilson <wilsons@start.ca>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        linux-kernel@vger.kernel.org, security@kernel.org
Subject: Re: [PATCH v3] proc: fix races against execve() of /proc/PID/fd**
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On Mon, 29 Aug 2011 22:00:11 +0400
Vasiliy Kulikov <segoon@openwall.com> wrote:

> Used existing (un)lock_trace functions to check for ptrace_may_access(),
> but instead of using EPERM return code from it use EACCES to be
> consistent with existing proc_pid_follow_link()/proc_pid_readlink()
> return code.  If they differ, attacker can guess what fds exist by
> analyzing stat() return code.

doh, I missed that bit.  Fair enough.