ice: Fix KASAN error in LAG NETDEV_UNREGISTER handler

Currently, the same handler is called for both a NETDEV_BONDING_INFO
LAG unlink notification as for a NETDEV_UNREGISTER call.  This is
causing a problem though, since the netdev_notifier_info passed has
a different structure depending on which event is passed.  The problem
manifests as a call trace from a BUG: KASAN stack-out-of-bounds error.

Fix this by creating a handler specific to NETDEV_UNREGISTER that only
is passed valid elements in the netdev_notifier_info struct for the
NETDEV_UNREGISTER event.

Also included is the removal of an unbalanced dev_put on the peer_netdev
and related braces.

Fixes: 6a8b3572 ("ice: Respond to a NETDEV_UNREGISTER event for LAG")
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Acked-by: Jonathan Toppins <jtoppins@redhat.com>
Tested-by: Sunitha Mekala <sunithax.d.mekala@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_lag.c

@@ -204,17 +204,39 @@ ice_lag_unlink(struct ice_lag *lag,
 		lag->upper_netdev = NULL;
 	}
 
-	if (lag->peer_netdev) {
-		dev_put(lag->peer_netdev);
-		lag->peer_netdev = NULL;
-	}
-
+	lag->peer_netdev = NULL;
 	ice_set_sriov_cap(pf);
 	ice_set_rdma_cap(pf);
 	lag->bonded = false;
 	lag->role = ICE_LAG_NONE;
 }
 
+/**
+ * ice_lag_unregister - handle netdev unregister events
+ * @lag: LAG info struct
+ * @netdev: netdev reporting the event
+ */
+static void ice_lag_unregister(struct ice_lag *lag, struct net_device *netdev)
+{
+	struct ice_pf *pf = lag->pf;
+
+	/* check to see if this event is for this netdev
+	 * check that we are in an aggregate
+	 */
+	if (netdev != lag->netdev || !lag->bonded)
+		return;
+
+	if (lag->upper_netdev) {
+		dev_put(lag->upper_netdev);
+		lag->upper_netdev = NULL;
+		ice_set_sriov_cap(pf);
+		ice_set_rdma_cap(pf);
+	}
+	/* perform some cleanup in case we come back */
+	lag->bonded = false;
+	lag->role = ICE_LAG_NONE;
+}
+
 /**
  * ice_lag_changeupper_event - handle LAG changeupper event
  * @lag: LAG info struct
@@ -307,7 +329,7 @@ ice_lag_event_handler(struct notifier_block *notif_blk, unsigned long event,
 		ice_lag_info_event(lag, ptr);
 		break;
 	case NETDEV_UNREGISTER:
-		ice_lag_unlink(lag, ptr);
+		ice_lag_unregister(lag, netdev);
 		break;
 	default:
 		break;