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From: David Howells <dhowells@redhat.com>
In-Reply-To: <20120409190350.GA14716@redhat.com>
References: <20120409190350.GA14716@redhat.com> <20120409190323.GA14712@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: dhowells@redhat.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 1/1] cred: copy_process() should clear child->replacement_session_keyring
Date: Wed, 11 Apr 2012 11:47:49 +0100
Message-ID: <14057.1334141269@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

Oleg Nesterov <oleg@redhat.com> wrote:

> keyctl_session_to_parent(task) sets ->replacement_session_keyring,
> it should be processed and cleared by key_replace_session_keyring().
> 
> However, this task can fork before it notices TIF_NOTIFY_RESUME and
> the new child gets the bogus ->replacement_session_keyring copied by
> dup_task_struct(). This is obviously wrong and, if nothing else, this
> leads to put_cred(already_freed_cred).
> 
> change copy_creds() to clear this member. If copy_process() fails
> before this point the wrong ->replacement_session_keyring doesn't
> matter, exit_creds() won't be called.
> 
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: David Howells <dhowells@redhat.com>