releases/4.9.212/inet-frags-call-inet_frags_fini-after-unregister_per.patch

From d821864061c6b6f2b656488e2239b6414c837cae Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Mon, 27 May 2019 16:56:48 -0700
Subject: 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 c01df341b5f64..5936bfafb1c43 100644
--- a/net/ieee802154/6lowpan/reassembly.c
+++ b/net/ieee802154/6lowpan/reassembly.c
@@ -633,7 +633,7 @@ err_sysctl:
 
 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 4aed9c45a91ad..3f488555999e3 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -592,8 +592,8 @@ err_protocol:
 
 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