[PATCH 4.9 78/97] netfilter: fix a use-after-free in mtype_destroy()

Greg Kroah-Hartman
2020-01-22T09:52:29Z

From: Cong Wang <xiyou.wangcong@gmail.com>

commit c120959387efa51479056fd01dc90adfba7a590c upstream.

map->members is freed by ip_set_free() right before using it in
mtype_ext_cleanup() again. So we just have to move it down.

Reported-by: syzbot+4c3cc6dbe7259dbf9054@syzkaller.appspotmail.com
Fixes: 40cd63bf33b2 ("netfilter: ipset: Support extensions which need a per data destroy function")
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/netfilter/ipset/ip_set_bitmap_gen.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/ipset/ip_set_bitmap_gen.h
+++ b/net/netfilter/ipset/ip_set_bitmap_gen.h
@@ -66,9 +66,9 @@ mtype_destroy(struct ip_set *set)
if (SET_WITH_TIMEOUT(set))
del_timer_sync(&map->gc);

- ip_set_free(map->members);
if (set->dsize && set->extensions & IPSET_EXT_DESTROY)
mtype_ext_cleanup(set);
+ ip_set_free(map->members);
ip_set_free(map);

set->data = NULL;