linux-kernel - [PATCH] xfrm6_tunnel: Fix potential panic when unloading xfrm6

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Date:   Thu, 14 Mar 2019 14:59:42 +0800
From:   Su Yanjun <suyj.fnst@...fujitsu.com>
To:     <steffen.klassert@...unet.com>, <herbert@...dor.apana.org.au>,
        <davem@...emloft.net>, <kuznet@....inr.ac.ru>,
        <yoshfuji@...ux-ipv6.org>
CC:     <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <suyj.fnst@...fujitsu.com>
Subject: [PATCH] xfrm6_tunnel: Fix potential panic when unloading xfrm6_tunnel module

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@...fujitsu.com>
---
 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 bc65db7..12cb3aa 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);
 }
 
-- 
2.7.4