[NETFILTER]: nf_conntrack: fix ct_extend ->move operation

The ->move operation has two bugs:

- It is called with the same extension as source and destination,
  so it doesn't update the new extension.

- The address of the old extension is calculated incorrectly,
  instead of (void *)ct->ext + ct->ext->offset[i] it uses
  ct->ext + ct->ext->offset[i].

Fixes a crash on x86_64 reported by Chuck Ebbert <cebbert@redhat.com>
and Thomas Woerner <twoerner@redhat.com>.
Tested-by: Thomas Woerner <twoerner@redhat.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_conntrack_extend.h

@@ -67,7 +67,7 @@ struct nf_ct_ext_type
 	void (*destroy)(struct nf_conn *ct);
 	/* Called when realloacted (can be NULL).
 	   Contents has already been moved. */
-	void (*move)(struct nf_conn *ct, void *old);
+	void (*move)(void *new, void *old);
 
 	enum nf_ct_ext_id id;
 

net/ipv4/netfilter/nf_nat_core.c

@@ -600,10 +600,10 @@ static void nf_nat_cleanup_conntrack(struct nf_conn *ct)
 	spin_unlock_bh(&nf_nat_lock);
 }
 
-static void nf_nat_move_storage(struct nf_conn *conntrack, void *old)
+static void nf_nat_move_storage(void *new, void *old)
 {
-	struct nf_conn_nat *new_nat = nf_ct_ext_find(conntrack, NF_CT_EXT_NAT);
-	struct nf_conn_nat *old_nat = (struct nf_conn_nat *)old;
+	struct nf_conn_nat *new_nat = new;
+	struct nf_conn_nat *old_nat = old;
 	struct nf_conn *ct = old_nat->ct;
 
 	if (!ct || !(ct->status & IPS_NAT_DONE_MASK))

net/netfilter/nf_conntrack_extend.c

@@ -109,7 +109,8 @@ void *__nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
 			rcu_read_lock();
 			t = rcu_dereference(nf_ct_ext_types[i]);
 			if (t && t->move)
-				t->move(ct, ct->ext + ct->ext->offset[i]);
+				t->move((void *)new + new->offset[i],
+					(void *)ct->ext + ct->ext->offset[i]);
 			rcu_read_unlock();
 		}
 		kfree(ct->ext);