Subject: Re: [PATCH 1/1] netfilter: nf_tables: fib: Drop IPV6 packages if IPv6 is disabled on boot

From: Florian Westphal <[email-masked]>
Date: Tue, 20 Aug 2019 07:36:07 +0200

Leonardo Bras <[email-masked]> wrote:
> If IPv6 is disabled on boot (ipv6.disable=1), but nft_fib_inet ends up
> dealing with a IPv6 package, 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
> 
> Fix this behavior by dropping IPv6 packages if !ipv6_mod_enabled().

Wouldn't fib_netdev.c have the same problem?

If so, might be better to place this test in both
nft_fib6_eval_type and nft_fib6_eval.