From: Witold Kręcicki <wpk@isc.org>
Date: Thu, 16 Jan 2020 10:52:58 +0000 (+0100)
Subject: netmgr: don't send to an inactive (closing) udp socket
X-Git-Tag: v9.16.0~60^2~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=16908ec3d912f0ca7e01edf95685eb91a52b4f08;p=thirdparty%2Fbind9.git

netmgr: don't send to an inactive (closing) udp socket

We had a race in which n UDP socket could have been already closing
by libuv but we still sent data to it. Mark socket as not-active
when stopping listening and verify that socket is not active when
trying to send data to it.
---

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index 177adec3c63..f309ab51318 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -603,6 +603,13 @@ isc__nmsocket_prep_destroy(isc_nmsocket_t *sock);
  * if there are no remaining references or active handles.
  */
 
+bool
+isc__nmsocket_active(isc_nmsocket_t *sock);
+/*%<
+ * Check is socket 'sock' is active - by checking either sock->active or
+ * sock->parent->active;
+ */
+
 void
 isc__nm_async_closecb(isc__networker_t *worker, isc__netievent_t *ev0);
 /*%<
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 6a66bd5fdbd..7943b1f5baf 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -681,7 +681,7 @@ isc__nm_enqueue_ievent(isc__networker_t *worker, isc__netievent_t *event) {
 	uv_async_send(&worker->async);
 }
 
-static bool
+bool
 isc__nmsocket_active(isc_nmsocket_t *sock) {
 	REQUIRE(VALID_NMSOCK(sock));
 	if (sock->parent != NULL) {
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 6b79d8e0bcf..0bad9ceaf5d 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -179,14 +179,18 @@ stop_udp_child(isc_nmsocket_t *sock) {
 
 static void
 stoplistening(isc_nmsocket_t *sock) {
+	INSIST(sock->type == isc_nm_udplistener);
 	/*
 	 * Socket is already closing; there's nothing to do.
 	 */
-	if (uv_is_closing((uv_handle_t *) &sock->uv_handle.udp)) {
+	if (!isc__nmsocket_active(sock)) {
 		return;
 	}
-
-	INSIST(sock->type == isc_nm_udplistener);
+	/*
+	 * Mark it inactive now so that all sends will be ignored
+	 * and we won't try to stop listening again.
+	 */
+	atomic_store(&sock->active, false);
 
 	for (int i = 0; i < sock->nchildren; i++) {
 		isc__netievent_udpstop_t *event = NULL;
@@ -375,6 +379,11 @@ isc__nm_udp_send(isc_nmhandle_t *handle, isc_region_t *region,
 		return (ISC_R_UNEXPECTED);
 	}
 
+	if (!isc__nmsocket_active(sock)) {
+		isc_nmhandle_unref(handle);
+		return (ISC_R_CANCELED);
+	}
+
 	if (isc__nm_in_netthread()) {
 		ntid = isc_nm_tid();
 	} else {
@@ -425,7 +434,7 @@ isc__nm_async_udpsend(isc__networker_t *worker, isc__netievent_t *ev0) {
 
 	REQUIRE(worker->id == ievent->sock->tid);
 
-	if (atomic_load(&ievent->sock->active)) {
+	if (isc__nmsocket_active(ievent->sock)) {
 		udp_send_direct(ievent->sock, ievent->req, &ievent->peer);
 	} else {
 		ievent->req->cb.send(ievent->req->handle,