From: Witold Kręcicki <wpk@isc.org>
Date: Thu, 16 Jan 2020 11:13:28 +0000 (+0100)
Subject: netmgr: fix a non-thread-safe access to libuv structures
X-Git-Tag: v9.16.0~60^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f75a9e32be18788bec50d714f76f538dfe366b19;p=thirdparty%2Fbind9.git

netmgr: fix a non-thread-safe access to libuv structures

In tcp and udp stoplistening code we accessed libuv structures
from a different thread, which caused a shutdown crash when named
was under load. Also added additional DbC checks making sure we're
in a proper thread when accessing uv_ functions.
---

diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index f309ab51318..7dfa8872e64 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -606,8 +606,8 @@ isc__nmsocket_prep_destroy(isc_nmsocket_t *sock);
 bool
 isc__nmsocket_active(isc_nmsocket_t *sock);
 /*%<
- * Check is socket 'sock' is active - by checking either sock->active or
- * sock->parent->active;
+ * Determine whether 'sock' is active by checking 'sock->active'
+ * or, for child sockets, 'sock->parent->active'.
  */
 
 void
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 17a97cda383..e0c566e176c 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -419,7 +419,7 @@ stoplistening(isc_nmsocket_t *sock) {
 		event = isc__nm_get_ievent(sock->mgr, netievent_tcpchildstop);
 		isc_nmsocket_attach(&sock->children[i], &event->sock);
 
-		if (i == sock->tid) {
+		if (isc_nm_tid() == sock->children[i].tid) {
 			isc__nm_async_tcpchildstop(&sock->mgr->workers[i],
 						   (isc__netievent_t *) event);
 			isc__nm_put_ievent(sock->mgr, event);
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index 0bad9ceaf5d..936fa963d9c 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -122,6 +122,7 @@ isc__nm_async_udplisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->type == isc_nm_udpsocket);
 	REQUIRE(sock->iface != NULL);
 	REQUIRE(sock->parent != NULL);
+	REQUIRE(sock->tid == isc_nm_tid());
 
 	uv_udp_init(&worker->loop, &sock->uv_handle.udp);
 	uv_handle_set_data(&sock->uv_handle.handle, NULL);
@@ -164,7 +165,8 @@ udp_close_cb(uv_handle_t *handle) {
 
 static void
 stop_udp_child(isc_nmsocket_t *sock) {
-	INSIST(sock->type == isc_nm_udpsocket);
+	REQUIRE(sock->type == isc_nm_udpsocket);
+	REQUIRE(sock->tid == isc_nm_tid());
 
 	uv_udp_recv_stop(&sock->uv_handle.udp);
 	uv_close((uv_handle_t *) &sock->uv_handle.udp, udp_close_cb);
@@ -179,13 +181,15 @@ stop_udp_child(isc_nmsocket_t *sock) {
 
 static void
 stoplistening(isc_nmsocket_t *sock) {
-	INSIST(sock->type == isc_nm_udplistener);
+	REQUIRE(sock->type == isc_nm_udplistener);
+
 	/*
 	 * Socket is already closing; there's nothing to do.
 	 */
 	if (!isc__nmsocket_active(sock)) {
 		return;
 	}
+
 	/*
 	 * Mark it inactive now so that all sends will be ignored
 	 * and we won't try to stop listening again.
@@ -195,7 +199,7 @@ stoplistening(isc_nmsocket_t *sock) {
 	for (int i = 0; i < sock->nchildren; i++) {
 		isc__netievent_udpstop_t *event = NULL;
 
-		if (i == sock->tid) {
+		if (isc_nm_tid() == sock->children[i].tid) {
 			stop_udp_child(&sock->children[i]);
 			continue;
 		}