IPVS netns exit causes crash in conntrack

Quote from Patric Mc Hardy
"This looks like nfnetlink.c excited and destroyed the nfnl socket, but
ip_vs was still holding a reference to a conntrack. When the conntrack
got destroyed it created a ctnetlink event, causing an oops in
netlink_has_listeners when trying to use the destroyed nfnetlink
socket."

If nf_conntrack_netlink is loaded before ip_vs this is not a problem.

This patch simply avoids calling ip_vs_conn_drop_conntrack()
when netns is dying as suggested by Julian.

Signed-off-by: Hans Schillstrom <hans.schillstrom@ericsson.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

2 files changed, 10 insertions, 1 deletions

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index bf28ac2fc99b..782db275ac53 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -776,8 +776,16 @@ static void ip_vs_conn_expire(unsigned long data)
                 if (cp->control)
                         ip_vs_control_del(cp);
 
-                if (cp->flags & IP_VS_CONN_F_NFCT)
+                if (cp->flags & IP_VS_CONN_F_NFCT) {
                         ip_vs_conn_drop_conntrack(cp);
+                        /* Do not access conntracks during subsys cleanup
+                         * because nf_conntrack_find_get can not be used after
+                         * conntrack cleanup for the net.
+                         */
+                        smp_rmb();
+                        if (ipvs->enable)
+                                ip_vs_conn_drop_conntrack(cp);
+                }
 
                 ip_vs_pe_put(cp->pe);
                 kfree(cp->pe_data);
diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
index 55af2242bccd..24c28d238dcb 100644
--- a/net/netfilter/ipvs/ip_vs_core.c
+++ b/net/netfilter/ipvs/ip_vs_core.c
@@ -1945,6 +1945,7 @@ static void __net_exit __ip_vs_dev_cleanup(struct net *net)
 {
         EnterFunction(2);
         net_ipvs(net)->enable = 0;      /* Disable packet reception */
+        smp_wmb();
         __ip_vs_sync_cleanup(net);
         LeaveFunction(2);
 }