From 583aea0f48640611f0c1d5da9dec8d3759521ce9 Mon Sep 17 00:00:00 2001
From: Andrew Jeddeloh <andrewjeddeloh@gmail.com>
Date: Thu, 31 Aug 2017 01:58:39 -0700
Subject: [PATCH] networkd: dont crash when mtu changes (#6594)

Prevent networkd from crashing when UseMTU is used. Many drivers will
bring the link down and then back up to configure a new MTU. Networkd
will also asynchonously send rtnl messages to configure the link and may
receive responses after the link has gone down and come back up (which
networkd will handle and set the lease and network to NULL.

This changes the behavior to instead return if this is the case instead
of crashing via assert.

(cherry picked from commit 0c9b15a38a558d8f84257455ee24174221069e9e)

Related: #1663365
---
 src/network/networkd-dhcp4.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index 295e44fdd7..a47286af6b 100644
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -57,8 +57,12 @@ static int link_set_dhcp_routes(Link *link) {
         int r, n, i;
 
         assert(link);
-        assert(link->dhcp_lease);
-        assert(link->network);
+
+        if (!link->dhcp_lease) /* link went down while we configured the IP addresses? */
+                return 0;
+
+        if (!link->network) /* link went down while we configured the IP addresses? */
+                return 0;
 
         if (!link->network->dhcp_routes)
                 return 0;