xfrm6_tunnel: Fix potential panic when unloading xfrm6_tunnel module

BugLink: https://bugs.launchpad.net/bugs/1838576
[ 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 <suyj.fnst@cn.fujitsu.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
index 3f7ffd3acc3949f8ff666352e7009e651bd70b14..b3fbf0acfa547652e4a5b293db574a47439da010 100644 (file)
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -399,6 +399,10 @@ 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);
 }