netdev - Re: [PATCH net 1/4] bonding: fix send_peer

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Date:   Wed, 26 Apr 2023 14:15:21 -0700
From:   Jay Vosburgh <jay.vosburgh@...onical.com>
To:     Hangbin Liu <liuhangbin@...il.com>
cc:     Jakub Kicinski <kuba@...nel.org>,
        kernel test robot <lkp@...el.com>, netdev@...r.kernel.org,
        oe-kbuild-all@...ts.linux.dev,
        "David S . Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Liang Li <liali@...hat.com>, Vincent Bernat <vincent@...nat.ch>
Subject: Re: [PATCH net 1/4] bonding: fix send_peer_notif overflow

Hangbin Liu <liuhangbin@...il.com> wrote:

>On Fri, Apr 21, 2023 at 05:55:16PM +0800, Hangbin Liu wrote:
>> > 	I'm fine to limit the peerf_notif_delay range and then use a
>> > smaller type.
>> > 
>> > 	num_peer_notif is already limited to 255; I'm going to suggest a
>> > limit to the delay of 300 seconds.  That seems like an absurdly long
>> > time for this; I didn't do any kind of science to come up with that
>> > number.
>> > 
>> > 	As peer_notif_delay is stored in units of miimon intervals, that
>> > gives a worst case peer_notif_delay value of 300000 if miimon is 1, and
>> > 255 * 300000 fits easily in a u32 for send_peer_notif.
>> 
>> OK, I just found another overflow. In bond_fill_info(),
>> or bond_option_miimon_set():
>> 
>>         if (nla_put_u32(skb, IFLA_BOND_PEER_NOTIF_DELAY,
>>                         bond->params.peer_notif_delay * bond->params.miimon))
>>                 goto nla_put_failure;
>> 
>> Since both peer_notif_delay and miimon are defined as int, there is a
>> possibility that the fill in number got overflowed. The same with up/down delay.
>> 
>> Even we limit the peer_notif_delay to 300s, which is 30000, there is still has
>> possibility got overflowed if we set miimon large enough.
>> 
>> This overflow should only has effect on use space shown since it's a
>> multiplication result. The kernel part works fine. I'm not sure if we should
>> also limit the miimon, up/down delay values..
>
>Hi Jay,
>
>Any comments for this issue? Should I send the send_peer_notif fix first and
>discuss the miimon, up/down delay userspace overflow issue later?

	Let's sort out the current send_peer_notif problems first.  I
don't see that the lack of upper bounds for miimon or up/down delay
causes issues for any reasonable configuration, so it can wait a bit.

	-J

---
	-Jay Vosburgh, jay.vosburgh@...onical.com