libn/d/overlay: don't deref nil PeerRecord on error

corhere · corhere · commit 12c6345d3aa4 · 2025-08-07T13:25:37.000-04:00
If unmarshaling the peer record fails, there is no need to check if it's
a record for a local peer. Attempting to do so anyway will result in a
nil-dereference panic. Don't do that.

The Windows overlay driver has a typo: prevPeer is being checked twice
for whether it was a local-peer record. Check prevPeer once and newPeer
once each, as intended.

Signed-off-by: Cory Snider &lt;csnider@mirantis.com&gt;
diff --git a/daemon/libnetwork/drivers/overlay/joinleave.go b/daemon/libnetwork/drivers/overlay/joinleave.go
@@ -174,8 +174,7 @@ func (d *driver) EventNotify(nid, tableName, key string, prev, value []byte) {
 		prevPeer, err = UnmarshalPeerRecord(prev)
 		if err != nil {
 			log.G(context.TODO()).WithError(err).Error("Failed to unmarshal previous peer record")
-		}
-		if prevPeer.TunnelEndpointIP == d.advertiseAddress {
+		} else if prevPeer.TunnelEndpointIP == d.advertiseAddress {
 			// Ignore local peers. We don't add them to the VXLAN
 			// FDB so don't need to remove them.
 			prevPeer = nil
@@ -186,8 +185,7 @@ func (d *driver) EventNotify(nid, tableName, key string, prev, value []byte) {
 		newPeer, err = UnmarshalPeerRecord(value)
 		if err != nil {
 			log.G(context.TODO()).WithError(err).Error("Failed to unmarshal peer record")
-		}
-		if newPeer.TunnelEndpointIP == d.advertiseAddress {
+		} else if newPeer.TunnelEndpointIP == d.advertiseAddress {
 			newPeer = nil
 		}
 	}
diff --git a/daemon/libnetwork/drivers/windows/overlay/joinleave_windows.go b/daemon/libnetwork/drivers/windows/overlay/joinleave_windows.go
@@ -74,8 +74,7 @@ func (d *driver) EventNotify(nid, tableName, key string, prev, value []byte) {
 		prevPeer, err = overlay.UnmarshalPeerRecord(prev)
 		if err != nil {
 			log.G(context.TODO()).WithError(err).Error("Failed to unmarshal previous peer record")
-		}
-		if prevPeer.TunnelEndpointIP.String() == n.providerAddress {
+		} else if prevPeer.TunnelEndpointIP.String() == n.providerAddress {
 			// Ignore local peers. We don't add them to the VXLAN
 			// FDB so don't need to remove them.
 			prevPeer = nil
@@ -86,8 +85,7 @@ func (d *driver) EventNotify(nid, tableName, key string, prev, value []byte) {
 		newPeer, err = overlay.UnmarshalPeerRecord(value)
 		if err != nil {
 			log.G(context.TODO()).WithError(err).Error("Failed to unmarshal peer record")
-		}
-		if prevPeer.TunnelEndpointIP.String() == n.providerAddress {
+		} else if newPeer.TunnelEndpointIP.String() == n.providerAddress {
 			newPeer = nil
 		}
 	}
