netdev - Re: [PATCH net v2] net: Fix icmp host relookup triggering ip_rt

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Message-ID: <CANn89iLxm+=_rm-GcJ2LenRTDThx2gkrqEJ-bEWqOGSxFVUw9Q@mail.gmail.com>
Date: Tue, 26 Nov 2024 18:26:37 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: David Ahern <dsahern@...nel.org>
Cc: Dong Chenchen <dongchenchen2@...wei.com>, davem@...emloft.net, pabeni@...hat.com, 
	horms@...nel.org, herbert@...dor.apana.org.au, steffen.klassert@...unet.com, 
	netdev@...r.kernel.org, yuehaibing@...wei.com, zhangchangzhong@...wei.com
Subject: Re: [PATCH net v2] net: Fix icmp host relookup triggering ip_rt_bug

\\

On Tue, Nov 26, 2024 at 5:23 PM David Ahern <dsahern@...nel.org> wrote:
>
> On 11/25/24 7:59 PM, Dong Chenchen wrote:
> > diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
> > index 4f088fa1c2f2..0d51f8434187 100644
> > --- a/net/ipv4/icmp.c
> > +++ b/net/ipv4/icmp.c
> > @@ -515,7 +515,10 @@ static struct rtable *icmp_route_lookup(struct net *net, struct flowi4 *fl4,
> >                         flowi4_to_flowi(fl4), NULL, 0);
> >       rt = dst_rtable(dst);
> >       if (!IS_ERR(dst)) {
> > -             if (rt != rt2)
> > +             unsigned int addr_type = inet_addr_type_dev_table(net,
> > +                                                     route_lookup_dev, fl4->daddr);
> > +
>
>         unsigned int addr_type;
>
>         addr_type = inet_addr_type_dev_table(net, route_lookup_dev,
>                                              fl4->daddr);
>
> allows the lines to meet column limits and alignment requirements.
>
> > +             if (rt != rt2 || c == RTN_LOCAL)
> >                       return rt;
> >       } else if (PTR_ERR(dst) == -EPERM) {
> >               rt = NULL;
>

Also, we can avoid the expensive call to  inet_addr_type_dev_table()
and addr_type variable with :

if (rt != rt2)
    return rt;
if (inet_addr_type_dev_table(net, route_lookup_dev,
                                               fl4->daddr) == RTN_LOCAL)
   return rt;