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

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Date:   Wed, 26 Apr 2023 15:03:45 +0800
From:   Hangbin Liu <liuhangbin@...il.com>
To:     Jay Vosburgh <jay.vosburgh@...onical.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

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?

Thanks
Hangbin