[SCSI] libfc, fcoe: ignore rx frame with wrong xid info

Drop the rx frame having xid with wrong cpu info
or received with xid  not matching to our xid.

Not dropping such frame is causing panic as
that causes accessing data struct beyond their
bounds.
Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/fcoe/fcoe.c

@@ -1373,6 +1373,10 @@ int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
 		} else
 			cpu = smp_processor_id();
 	}
+
+	if (cpu >= nr_cpu_ids)
+		goto err;
+
 	fps = &per_cpu(fcoe_percpu, cpu);
 	spin_lock_bh(&fps->fcoe_rx_list.lock);
 	if (unlikely(!fps->thread)) {

drivers/scsi/libfc/fc_exch.c

@@ -802,10 +802,8 @@ static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid)
 		pool = per_cpu_ptr(mp->pool, xid & fc_cpu_mask);
 		spin_lock_bh(&pool->lock);
 		ep = fc_exch_ptr_get(pool, (xid - mp->min_xid) >> fc_cpu_order);
-		if (ep) {
+		if (ep && ep->xid == xid)
 			fc_exch_hold(ep);
-			WARN_ON(ep->xid != xid);
-		}
 		spin_unlock_bh(&pool->lock);
 	}
 	return ep;