From: Evan Hunt <each@isc.org>
Date: Fri, 21 Apr 2017 00:42:03 +0000 (-0700)
Subject: [v9_10] fix dispatch.c shutdown race
X-Git-Tag: v9.10.6b1~125
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=70590c691b410303ac44f879e0a3b2b58711a3de;p=thirdparty%2Fbind9.git

[v9_10] fix dispatch.c shutdown race

4952.	[bug]		A race condition on shutdown could trigger an
			assertion failure in dispatch.c. [RT #43822]

(cherry picked from commit 019132b70c368bc9abca0034d07b324bb7cb6eb2)
---

diff --git a/CHANGES b/CHANGES
index baeec24538c..23675c0e998 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4952.	[bug]		A race condition on shutdown could trigger an
+			assertion failure in dispatch.c. [RT #43822]
+
 4591.	[port]		Addressed some python 3 compatibility issues.
 			Thanks to Ville Skytta. [RT #44955] [RT #44956]
 
diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
index 3371af0baa4..8122a743d85 100644
--- a/lib/dns/dispatch.c
+++ b/lib/dns/dispatch.c
@@ -3688,9 +3688,12 @@ dns_dispatch_importrecv(dns_dispatch_t *disp, isc_event_t *event) {
 	REQUIRE((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) != 0);
 	REQUIRE(event != NULL);
 
-	sevent = (isc_socketevent_t *)event;
+	if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) == 0)
+		return;
 
+	sevent = (isc_socketevent_t *)event;
 	INSIST(sevent->n <= disp->mgr->buffersize);
+
 	newsevent = (isc_socketevent_t *)
 		    isc_event_allocate(disp->mgr->mctx, NULL,
 				      DNS_EVENT_IMPORTRECVDONE, udp_shrecv,
diff --git a/lib/dns/include/dns/dispatch.h b/lib/dns/include/dns/dispatch.h
index f936f68c345..a692de4ca8a 100644
--- a/lib/dns/include/dns/dispatch.h
+++ b/lib/dns/include/dns/dispatch.h
@@ -524,6 +524,9 @@ dns_dispatch_importrecv(dns_dispatch_t *disp, isc_event_t *event);
  * shared between dispatchers and clients.  If the dispatcher fails to copy
  * or send the event, nothing happens.
  *
+ * If the attribute DNS_DISPATCHATTR_NOLISTEN is not set, then
+ * the dispatch is already handling a recv; return immediately.
+ *
  * Requires:
  *\li 	disp is valid, and the attribute DNS_DISPATCHATTR_NOLISTEN is set.
  * 	event != NULL