From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Wed, 2 Oct 2019 08:29:41 +0000 (+0200)
Subject: sd-dhcp-client: do not crash if sd_dhcp_client_send_release() is called with no lease
X-Git-Tag: v244-rc1~234^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F13696%2Fhead;p=thirdparty%2Fsystemd.git

sd-dhcp-client: do not crash if sd_dhcp_client_send_release() is called with no lease

Again, a public function should not crash if called at an inopportune moment.

Also, make sure we don't call the function if we have no lease.
---

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 3f386db2f55..02f3569edca 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -1895,6 +1895,7 @@ int sd_dhcp_client_start(sd_dhcp_client *client) {
 int sd_dhcp_client_send_release(sd_dhcp_client *client) {
         assert_return(client, -EINVAL);
         assert_return(client->state != DHCP_STATE_STOPPED, -ESTALE);
+        assert_return(client->lease, -EUNATCH);
 
         _cleanup_free_ DHCPPacket *release = NULL;
         size_t optoffset, optlen;
diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index 78cd2411402..db762163a88 100644
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -864,10 +864,10 @@ static int dhcp4_handler(sd_dhcp_client *client, int event, void *userdata) {
                                 return 0;
                         }
 
-                        if (link->network->dhcp_send_release)
-                                (void) sd_dhcp_client_send_release(client);
-
                         if (link->dhcp_lease) {
+                                if (link->network->dhcp_send_release)
+                                        (void) sd_dhcp_client_send_release(client);
+
                                 r = dhcp_lease_lost(link);
                                 if (r < 0) {
                                         link_enter_failed(link);