From a47c13a7a2cd66644adf2459690f9c3bb96235ab Mon Sep 17 00:00:00 2001
From: Beniamino Galvani <bgalvani@redhat.com>
Date: Thu, 28 Apr 2016 22:48:39 +0200
Subject: [PATCH] device: postpone updates of IP configuration when a commit is
 pending

When a new dynamic configuration is received, it is stored in a member
of private structure (e.g. @dhcp6_ip6_config) and a commit is
scheduled. Before the commit is executed, an update_ipx_config() could
be called and it would change the configuration before it is
committed.

This race condition causes failures in assigning the addresses
received through DHCPv6 when the internal client is used (but
potentially other clients and methods are affected).

To fix it, postpone updates of IP configurations when a commit is
already pending.
---
 src/devices/nm-device.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index dd0dbb18b8..a01e94841a 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -3425,6 +3425,15 @@ activation_source_schedule (NMDevice *self, ActivationHandleFunc func, int famil
 	act_data->id = new_id;
 }
 
+static gboolean
+activation_source_is_scheduled (NMDevice *self, ActivationHandleFunc func, int family)
+{
+	ActivationHandleData *act_data;
+
+	act_data = activation_source_get_by_family (self, family, NULL);
+	return act_data->func == func;
+}
+
 /*****************************************************************************/
 
 static gboolean
@@ -8823,6 +8832,18 @@ update_ip4_config (NMDevice *self, gboolean initial)
 	int ifindex;
 	gboolean capture_resolv_conf;
 
+	/* If a commit is scheduled, this function would potentially interfere with
+	 * it changing IP configurations before they are applied. Postpone the
+	 * update in such case.
+	 */
+	if (activation_source_is_scheduled (self,
+	                                    activate_stage5_ip4_config_commit,
+	                                    AF_INET)) {
+		priv->queued_ip4_config_id = g_idle_add (queued_ip4_config_change, self);
+		_LOGT (LOGD_DEVICE, "IP4 update was postponed");
+		return;
+	}
+
 	ifindex = nm_device_get_ip_ifindex (self);
 	if (!ifindex)
 		return;
@@ -8900,6 +8921,18 @@ update_ip6_config (NMDevice *self, gboolean initial)
 	int ifindex;
 	gboolean capture_resolv_conf;
 
+	/* If a commit is scheduled, this function would potentially interfere with
+	 * it changing IP configurations before they are applied. Postpone the
+	 * update in such case.
+	 */
+	if (activation_source_is_scheduled (self,
+	                                    activate_stage5_ip6_config_commit,
+	                                    AF_INET6)) {
+		priv->queued_ip6_config_id = g_idle_add (queued_ip6_config_change, self);
+		_LOGT (LOGD_DEVICE, "IP6 update was postponed");
+		return;
+	}
+
 	ifindex = nm_device_get_ip_ifindex (self);
 	if (!ifindex)
 		return;