[NETFILTER]: Wait until all references to ip_conntrack_untracked are dropped on unload

Fixes a crash when unloading ip_conntrack.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/ip_conntrack_core.c b/net/ipv4/netfilter/ip_conntrack_core.c
index 14af55cad5d6..63bf88264980 100644
--- a/net/ipv4/netfilter/ip_conntrack_core.c
+++ b/net/ipv4/netfilter/ip_conntrack_core.c
@@ -1107,6 +1107,9 @@ void ip_conntrack_cleanup(void)
                 schedule();
                 goto i_see_dead_people;
         }
+        /* wait until all references to ip_conntrack_untracked are dropped */
+        while (atomic_read(&ip_conntrack_untracked.ct_general.use) > 1)
+                schedule();
 
         kmem_cache_destroy(ip_conntrack_cachep);
         kmem_cache_destroy(ip_conntrack_expect_cachep);