From: ebiederm@xmission•com (Eric W. Biederman)
To: sjur.brandeland@stericsson•com
Cc: davem@davemloft•net, netdev@vger•kernel.org, sjurbren@gmail•com,
Dmitry Tarnyagin <dmitry.tarnyagin@stericsson•com>
Subject: Re: [PATCH net] caif: Fix access to freed pernet memory
Date: Sun, 15 Jul 2012 18:43:14 -0700 [thread overview]
Message-ID: <87zk70tr9p.fsf@xmission.com> (raw)
In-Reply-To: <1342383014-5525-1-git-send-email-sjur.brandeland@stericsson.com> (sjur brandeland's message of "Sun, 15 Jul 2012 22:10:14 +0200")
sjur.brandeland@stericsson•com writes:
> From: Sjur Brændeland <sjur.brandeland@stericsson•com>
>
> 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:
Acked-by: "Eric W. Biederman" <ebiederm@xmission•com>
The patch looks good to me.
You might want to look at error handling during caif_device_init
as well, as it looks like the same ordering issue is present.
Although unlikely to bite anyone at that point.
Eric
>
> 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@stericsson•com>
> ---
>
> Hi Dave,
>
> Can you please queue up this bugfix as appropriate for -net and -stable?
>
> I guess this bug has been around since introduction of network
> name spaces in CAIF, but it became visible after 3.4 and the commit:
> "net: In unregister_netdevice_notifier unregister the netdevices."
>
> Thanks,
> Sjur
>
> net/caif/caif_dev.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
> index 554b312..8c83c17 100644
> --- a/net/caif/caif_dev.c
> +++ b/net/caif/caif_dev.c
> @@ -561,9 +561,9 @@ 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);
next prev parent reply other threads:[~2012-07-16 1:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-15 20:10 [PATCH net] caif: Fix access to freed pernet memory sjur.brandeland
2012-07-16 1:43 ` Eric W. Biederman [this message]
2012-07-17 6:06 ` David Miller
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