linux-kernel - [PATCH AUTOSEL 4.4 2/8] xfrm6_tunnel: Fix potential panic when unloading xfrm6

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Message-Id: <20190516114146.9267-2-sashal@kernel.org>
Date:   Thu, 16 May 2019 07:41:40 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Su Yanjun <suyj.fnst@...fujitsu.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 2/8] xfrm6_tunnel: Fix potential panic when unloading xfrm6_tunnel module

From: Su Yanjun <suyj.fnst@...fujitsu.com>

[ 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@...fujitsu.com>
Acked-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 56b72cada346f..f9d493c59d6c1 100644
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -391,6 +391,10 @@ 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