netdev - [Patch net] netfilter: fix a use-after-free in mtype

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Date:   Fri, 10 Jan 2020 11:53:08 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     netfilter-devel@...r.kernel.org,
        Cong Wang <xiyou.wangcong@...il.com>,
        syzbot+4c3cc6dbe7259dbf9054@...kaller.appspotmail.com,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>
Subject: [Patch net] netfilter: fix a use-after-free in mtype_destroy()

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@...kaller.appspotmail.com
Fixes: 40cd63bf33b2 ("netfilter: ipset: Support extensions which need a per data destroy function")
Cc: Pablo Neira Ayuso <pablo@...filter.org>
Acked-by: Jozsef Kadlecsik <kadlec@...filter.org>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/netfilter/ipset/ip_set_bitmap_gen.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipset/ip_set_bitmap_gen.h b/net/netfilter/ipset/ip_set_bitmap_gen.h
index 1abd6f0dc227..077a2cb65fcb 100644
--- a/net/netfilter/ipset/ip_set_bitmap_gen.h
+++ b/net/netfilter/ipset/ip_set_bitmap_gen.h
@@ -60,9 +60,9 @@ 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;
-- 
2.21.1