From: Dan Carpenter <error27@gmail.com>
Date: Mon, 28 Mar 2011 08:50:48 +0000
Subject: [patch -next] ipcns: use after free in free_ipc_ns()
Message-Id: <20110328085048.GI1885@bicker>
List-Id: <kernel-janitors.vger.kernel.org>
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To: Andrew Morton <akpm@linux-foundation.org>
Cc: serge@hallyn.com, "Eric W. Biederman" <ebiederm@xmission.com>, David Howells <dhowells@redhat.com>, Daniel Lezcano <daniel.lezcano@free.fr>, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org

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

Signed-off-by: Dan Carpenter <error27@gmail.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);
 }
 
 /*