Re: [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled

From: Pablo Neira Ayuso
Date: Tue Sep 03 2019 - 16:55:41 EST

On Fri, Aug 30, 2019 at 03:13:53PM -0300, Leonardo Bras 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.

Patch is applied, thanks.