Subject: [PATCH AUTOSEL 5.0 03/34] xfrm6_tunnel: Fix potential panic when unloading xfrm6_tunnel module

From: Sasha Levin <[email-masked]>
Date: Thu, 16 May 2019 07:39:00 -0400

From: Su Yanjun <[email-masked]>

[ Upstream commit 6ee02a54ef990a71bf542b6f0a4e3321de9d9c66 ]

When unloading xfrm6_tunnel module, xfrm6_tunnel_fini directly
frees the xfrm6_tunnel_spi_kmem. Maybe someone has gotten the
xfrm6_tunnel_spi, so need to wait it.

Fixes: 91cc3bb0b04ff("xfrm6_tunnel: RCU conversion")
Signed-off-by: Su Yanjun <[email-masked]>
Acked-by: Herbert Xu <[email-masked]>
Signed-off-by: Steffen Klassert <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 net/ipv6/xfrm6_tunnel.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
index bc65db782bfb1..12cb3aa990af4 100644
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -402,6 +402,10 @@ static void __exit xfrm6_tunnel_fini(void)
 	xfrm6_tunnel_deregister(&xfrm6_tunnel_handler, AF_INET6);
 	xfrm_unregister_type(&xfrm6_tunnel_type, AF_INET6);
 	unregister_pernet_subsys(&xfrm6_tunnel_net_ops);
+	/* Someone maybe has gotten the xfrm6_tunnel_spi.
+	 * So need to wait it.
+	 */
+	rcu_barrier();
 	kmem_cache_destroy(xfrm6_tunnel_spi_kmem);
 }
 
-- 
2.20.1