[PATCH v2 2/2] netfilter: ip6_tables: guard ip6t_unregister_table_pre_exit against NULL ops

[Tristan Madani <tristmd@gmail.com>]

Same race as the ipv4 counterpart: ip6t_register_table() adds the
table to the per-netns list before assigning new_table->ops.
cleanup_net can find the table with a NULL ops pointer and crash in
nf_unregister_net_hooks().

Guard against this by checking table->ops before the call.

Fixes: ee177a54413a ("netfilter: ip6_tables: Use xt_register_table()")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 net/ipv6/netfilter/ip6_tables.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index XXXXXXX..XXXXXXX 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1804,7 +1804,7 @@ void ip6t_unregister_table_pre_exit(struct net *net, const char *name)
 {
 	struct xt_table *table = xt_find_table(net, NFPROTO_IPV6, name);

-	if (table)
+	if (table && table->ops)
 		nf_unregister_net_hooks(net, table->ops, hweight32(table->valid_hooks));
 }