linux-kernel - Re: [patch -next] ipcns: use after free in free_ipc

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Date:	Mon, 28 Mar 2011 04:55:31 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Dan Carpenter <error27@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, serge@...lyn.com,
	David Howells <dhowells@...hat.com>,
	Daniel Lezcano <daniel.lezcano@...e.fr>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch -next] ipcns: use after free in free_ipc_ns()

Dan Carpenter <error27@...il.com> writes:

> We dereference "ns" after it has been freed.  This was introduced in
> b515498f5bb5 "userns: add a user namespace owner of ipc ns".

I think Andrew has already merged this fix.


>
> Signed-off-by: Dan Carpenter <error27@...il.com>
>
> diff --git a/ipc/namespace.c b/ipc/namespace.c
> index 3c3e522..8054c8e 100644
> --- a/ipc/namespace.c
> +++ b/ipc/namespace.c
> @@ -104,7 +104,6 @@ static void free_ipc_ns(struct ipc_namespace *ns)
>  	sem_exit_ns(ns);
>  	msg_exit_ns(ns);
>  	shm_exit_ns(ns);
> -	kfree(ns);
>  	atomic_dec(&nr_ipc_ns);
>  
>  	/*
> @@ -113,6 +112,7 @@ static void free_ipc_ns(struct ipc_namespace *ns)
>  	 */
>  	ipcns_notify(IPCNS_REMOVED);
>  	put_user_ns(ns->user_ns);
> +	kfree(ns);
>  }
>  
>  /*
--
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