Subject: Re: [PATCH v1] i40e: Add length check for IFLA_AF_SPEC parsing

From: Leon Romanovsky <[email-masked]>
Date: Tue, 25 Jul 2023 08:40:46 +0300

On Mon, Jul 24, 2023 at 02:21:55PM -0700, Jakub Kicinski wrote:
> On Mon, 24 Jul 2023 20:44:35 +0300 Leon Romanovsky wrote:
> > > @@ -13186,6 +13186,9 @@ static int i40e_ndo_bridge_setlink(struct net_device *dev,
> > >  		if (nla_type(attr) != IFLA_BRIDGE_MODE)
> > >  			continue;
> > >  
> > > +		if (nla_len(attr) < sizeof(mode))
> > > +			return -EINVAL;
> > > +  
> > 
> > I see that you added this hunk to all users of nla_for_each_nested(), it
> > will be great to make that iterator to skip such empty attributes.
> > 
> > However, i don't know nettlink good enough to say if your change is
> > valid in first place.
> 
> Empty attributes are valid, we can't do that.

Maybe Lin can add special version of nla_for_each_nested() which will
skip these empty NLAs, for code which don't allow empty attributes.

> 
> But there's a loop in rtnl_bridge_setlink() which checks the attributes.
> We can add the check there instead of all users, as Leon points out.
> (Please just double check that all ndo_bridge_setlink implementation
> expect this value to be a u16, they should/)
> -- 
> pw-bot: cr