netdev - Re: [PATCH net v2]bonding: fix send_peer

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Date:   Thu, 28 Jan 2021 12:46:23 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     liaichun <liaichun@...wei.com>
Cc:     "davem@...emloft.net" <davem@...emloft.net>,
        "j.vosburgh@...il.com" <j.vosburgh@...il.com>,
        "vfalico@...il.com" <vfalico@...il.com>,
        "andy@...yhouse.net" <andy@...yhouse.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Vincent Bernat <vincent@...nat.ch>
Subject: Re: [PATCH net v2]bonding: fix send_peer_notif data truncation

Please make sure you CC the author of the original code.

On Wed, 27 Jan 2021 03:57:22 +0000 liaichun wrote:
> send_peer_notif is u8, the value of this parameter is obtained from
>  u8*int, it's easy to be truncated. And in practice, more than u8(256)
>   characters are used.

Did you find this through code inspection of is it really a problem?
What's your miimon setting?

> Fixes: 07a4ddec3ce9 ("bonding: add an option to specify a delay between peer notifications")
> Signed-off-by: Aichun Li <liaichun@...wei.com>
> ---
>  include/net/bonding.h | 2 +-
>  drivers/net/bonding/bond_main.c | 4 ++--
>  2 file changed, 3 insertion(+), 3 deletion(-)
> 
> diff --git a/include/net/bonding.h b/include/net/bonding.h index 0960d9af7b8e..65394566d556 100644
> --- a/include/net/bonding.h
> +++ b/include/net/bonding.h
> @@ -215,7 +215,7 @@ struct bonding {
>  	 */
>  	spinlock_t mode_lock;
>  	spinlock_t stats_lock;
> -	u8	 send_peer_notif;
> +	u32	 send_peer_notif;
>  	u8       igmp_retrans;
>  #ifdef CONFIG_PROC_FS
>  	struct   proc_dir_entry *proc_entry;
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index b7db57e6c96a..336460538135 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -880,8 +880,8 @@ void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
>  
>  			if (netif_running(bond->dev)) {
>  				bond->send_peer_notif =
> -					bond->params.num_peer_notif *
> -					max(1, bond->params.peer_notif_delay);
> +					(u32)(bond->params.num_peer_notif *

Why do you add the cast?

> +					max(1, bond->params.peer_notif_delay));
>  				should_notify_peers =
>  					bond_should_notify_peers(bond);
>  			}
> --
> 2.19.1
>