From: Jay Vosburgh <fubar@us.ibm.com>
To: David Miller <davem@davemloft.net>
Cc: mitsuo.hayasaka.hu@hitachi.com, andy@greyhouse.net,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
yrl.pp-manager.tt@hitachi.com, eric.dumazet@gmail.com,
xiyou.wangcong@gmail.com
Subject: Re: [PATCH net -v2] [BUGFIX] bonding: use local function pointer of bond->recv_probe in bond_handle_frame
Date: Wed, 19 Oct 2011 10:59:07 -0700 [thread overview]
Message-ID: <26928.1319047147@death> (raw)
In-Reply-To: <20111019.000311.1490092497677136273.davem@davemloft.net>
David Miller <davem@davemloft.net> wrote:
>From: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
>Date: Thu, 13 Oct 2011 11:04:29 +0900
>
>> The bond->recv_probe is called in bond_handle_frame() when
>> a packet is received, but bond_close() sets it to NULL. So,
>> a panic occurs when both functions work in parallel.
>>
>> Why this happen:
>> After null pointer check of bond->recv_probe, an sk_buff is
>> duplicated and bond->recv_probe is called in bond_handle_frame.
>> So, a panic occurs when bond_close() is called between the
>> check and call of bond->recv_probe.
>>
>> Patch:
>> This patch uses a local function pointer of bond->recv_probe
>> in bond_handle_frame(). So, it can avoid the null pointer
>> dereference.
>>
>>
>> Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
>> Cc: Jay Vosburgh <fubar@us.ibm.com>
>> Cc: Andy Gospodarek <andy@greyhouse.net>
>> Cc: Eric Dumazet <eric.dumazet@gmail.com>
>> Cc: WANG Cong <xiyou.wangcong@gmail.com>
>
>Bonding folks please review this, thanks.
>
Looks reasonable. Even if by some quirk of timing the
recv_probe function ends up being entered after bond_close has
completed, it doesn't look like there is a risk of those functions
misbehaving (because bond_close doesn't deallocate the data structures).
-J
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
---
-Jay Vosburgh, IBM Linux Technology Center, fubar@us.ibm.com
next prev parent reply other threads:[~2011-10-19 18:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-13 2:04 [PATCH net -v2] [BUGFIX] bonding: use local function pointer of bond->recv_probe in bond_handle_frame Mitsuo Hayasaka
2011-10-19 4:03 ` David Miller
2011-10-19 17:59 ` Jay Vosburgh [this message]
2011-10-19 4:05 ` Eric Dumazet
2011-10-19 4:14 ` David Miller
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