On Tue, Sep 03, 2019 at 07:05:50PM +0200, Florian Westphal wrote: > Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote: > > On Tue, Sep 03, 2019 at 01:46:50PM -0300, Leonardo Bras wrote: > > > On Fri, 2019-08-30 at 22:58 +0200, Florian Westphal wrote: > > > > Leonardo Bras <leonardo@xxxxxxxxxxxxx> wrote: > > > > > If IPv6 is disabled on boot (ipv6.disable=1), but nft_fib_inet ends up > > > > > dealing with a IPv6 packet, it causes a kernel panic in > > > > > fib6_node_lookup_1(), crashing in bad_page_fault. > > > > > > > > > > The panic is caused by trying to deference a very low address (0x38 > > > > > in ppc64le), due to ipv6.fib6_main_tbl = NULL. > > > > > BUG: Kernel NULL pointer dereference at 0x00000038 > > > > > > > > > > The kernel panic was reproduced in a host that disabled IPv6 on boot and > > > > > have to process guest packets (coming from a bridge) using it's ip6tables. > > > > > > > > > > Terminate rule evaluation when packet protocol is IPv6 but the ipv6 module > > > > > is not loaded. > > > > > > > > > > Signed-off-by: Leonardo Bras <leonardo@xxxxxxxxxxxxx> > > > > > > > > Acked-by: Florian Westphal <fw@xxxxxxxxx> > > > > > > > > > > Hello Pablo, > > > > > > Any trouble with this patch? > > > I could see the other* one got applied, but not this one. > > > *(The other did not get acked, so i released it alone as v5) > > > > > > Is there any fix I need to do in this one? > > > > Hm, I see, so this one: > > > > https://patchwork.ozlabs.org/patch/1156100/ > > > > is not enough? > > No, its not. > > > I was expecting we could find a way to handle this from br_netfilter > > alone itself. > > We can't because we support ipv6 fib lookups from the netdev family > as well. > > Alternative is to auto-accept ipv6 packets from the nf_tables eval loop, > but I think its worse. Could we add a restriction for nf_tables + br_netfilter + !ipv6. I mean, if this is an IPv6 packet, nf_tables is on and IPv6 module if off, then drop this packet? By dropping packet, the user could diagnose that its setup is incomplete. I mean, if nf_tables fib ipv6 is used, then this setup is really wrong and the user forgots to load the ipv6 module.
