[PATCH AUTOSEL 4.19 385/671] inet: frags: call inet_frags_fini() after unregister_pernet_subsys()

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit ae7352d384a552d8c799c242e74a934809990a71 ]

Both IPv6 and 6lowpan are calling inet_frags_fini() too soon.

inet_frags_fini() is dismantling a kmem_cache, that might be needed
later when unregister_pernet_subsys() eventually has to remove
frags queues from hash tables and free them.

This fixes potential use-after-free, and is a prereq for the following patch.

Fixes: d4ad4d22e7ac ("inet: frags: use kmem_cache for inet_frag_queue")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ieee802154/6lowpan/reassembly.c | 2 +-
 net/ipv6/reassembly.c               | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ieee802154/6lowpan/reassembly.c b/net/ieee802154/6lowpan/reassembly.c
index e7857a8ac86d..f3074249c6fc 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c

@@ -629,7 +629,7 @@ int __init lowpan_net_frag_init(void)
 
 void lowpan_net_frag_exit(void)
 {
-	inet_frags_fini(&lowpan_frags);
 	lowpan_frags_sysctl_unregister();
 	unregister_pernet_subsys(&lowpan_frags_ops);
+	inet_frags_fini(&lowpan_frags);
 }

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 095825f964e2..c6132e39ab16 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c

@@ -593,8 +593,8 @@ int __init ipv6_frag_init(void)
 
 void ipv6_frag_exit(void)
 {
-	inet_frags_fini(&ip6_frags);
 	ip6_frags_sysctl_unregister();
 	unregister_pernet_subsys(&ip6_frags_ops);
 	inet6_del_protocol(&frag_protocol, IPPROTO_FRAGMENT);
+	inet_frags_fini(&ip6_frags);
 }

-- 
2.20.1