net: sched: cls_u32: rcu can not be last node

tc_u32_sel 'sel' in tc_u_knode expects to be the last element in the
structure and pads the structure with tc_u32_key fields for each key.

 kzalloc(sizeof(*n) + s->nkeys*sizeof(struct tc_u32_key), GFP_KERNEL)

CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/cls_u32.c

@@ -64,8 +64,11 @@ struct tc_u_knode {
 	u32 __percpu		*pcpu_success;
 #endif
 	struct tcf_proto	*tp;
-	struct tc_u32_sel	sel;
 	struct rcu_head		rcu;
+	/* The 'sel' field MUST be the last field in structure to allow for
+	 * tc_u32_keys allocated at end of structure.
+	 */
+	struct tc_u32_sel	sel;
 };
 
 struct tc_u_hnode {