From cc2722424ef55918f6feee45958eedf0b3eddd51 Mon Sep 17 00:00:00 2001
From: Wade Simmons <wsimmons@slack-corp.com>
Date: Thu, 24 Jul 2025 16:23:36 -0400
Subject: [PATCH] netlink: ignore route updates with no destination

Currently we assume each route update must have a destination, but we
should check that it is set before we try to use it.

See: #1436
---
 overlay/tun_linux.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/overlay/tun_linux.go b/overlay/tun_linux.go
index 4c509ba..00e3284 100644
--- a/overlay/tun_linux.go
+++ b/overlay/tun_linux.go
@@ -638,6 +638,11 @@ func (t *tun) updateRoutes(r netlink.RouteUpdate) {
 		return
 	}
 
+	if r.Dst == nil {
+		t.l.WithField("route", r).Debug("Ignoring route update, no destination address")
+		return
+	}
+
 	dstAddr, ok := netip.AddrFromSlice(r.Dst.IP)
 	if !ok {
 		t.l.WithField("route", r).Debug("Ignoring route update, invalid destination address")