linux-kernel - [ 04/37] caif: Fix access to freed pernet memory

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Message-Id: <20120817030244.417737302@decadent.org.uk>
Date:	Fri, 17 Aug 2012 04:02:47 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Sjur Brændeland <sjur.brandeland@...ricsson.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 04/37] caif: Fix access to freed pernet memory

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sjur Brændeland <sjur.brandeland@...ricsson.com>

[ Upstream commit 96f80d123eff05c3cd4701463786b87952a6c3ac ]

unregister_netdevice_notifier() must be called before
unregister_pernet_subsys() to avoid accessing already freed
pernet memory. This fixes the following oops when doing rmmod:

Call Trace:
 [<ffffffffa0f802bd>] caif_device_notify+0x4d/0x5a0 [caif]
 [<ffffffff81552ba9>] unregister_netdevice_notifier+0xb9/0x100
 [<ffffffffa0f86dcc>] caif_device_exit+0x1c/0x250 [caif]
 [<ffffffff810e7734>] sys_delete_module+0x1a4/0x300
 [<ffffffff810da82d>] ? trace_hardirqs_on_caller+0x15d/0x1e0
 [<ffffffff813517de>] ? trace_hardirqs_on_thunk+0x3a/0x3
 [<ffffffff81696bad>] system_call_fastpath+0x1a/0x1f

RIP
 [<ffffffffa0f7f561>] caif_get+0x51/0xb0 [caif]

Signed-off-by: Sjur Brændeland <sjur.brandeland@...ricsson.com>
Acked-by: "Eric W. Biederman" <ebiederm@...ssion.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/caif/caif_dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 68223e4..4e9115d 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c
@@ -428,9 +428,9 @@ static int __init caif_device_init(void)
 
 static void __exit caif_device_exit(void)
 {
-	unregister_pernet_subsys(&caif_net_ops);
 	unregister_netdevice_notifier(&caif_device_notifier);
 	dev_remove_pack(&caif_packet_type);
+	unregister_pernet_subsys(&caif_net_ops);
 }
 
 module_init(caif_device_init);


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