Linux Ethernet Bridging - Sep 2019 - [Bridge] [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled

On Fri, 2019-08-30 at 22:58 +0200, Florian Westphal
wrote:
> Leonardo Bras <leonardo at linux.ibm.com> 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 at linux.ibm.com>
> 
> Acked-by: Florian Westphal <fw at strlen.de>
> 
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?

Best regards,
Leonardo Bras
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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 at linux.ibm.com> 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 at linux.ibm.com>
> > 
> > Acked-by: Florian Westphal <fw at strlen.de>
> > 
> 
> 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?

I was expecting we could find a way to handle this from br_netfilter
alone itself.

Thanks.