From: Evan Hunt <each@isc.org>
Date: Mon, 9 Nov 2020 20:33:37 +0000 (-0800)
Subject: address some possible shutdown races in xfrin
X-Git-Tag: v9.16.11~17^2~24
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f6f0e26ab401c38ca67559f23fc8129d5bcc037;p=thirdparty%2Fbind9.git

address some possible shutdown races in xfrin

there were two failures during observed in testing, both occurring
when 'rndc halt' was run rather than 'rndc stop' - the latter dumps
zone contents to disk and presumably introduced enough delay to
prevent the races:

- a failure when the zone was shut down and called dns_xfrin_detach()
  before the xfrin had finished connecting; the connect timeout
  terminated without detaching its handle
- a failure when the tcpdns socket timer fired after the outerhandle
  had already been cleared.

this commit incidentally addresses a failure observed in mutexatomic
due to a variable having been initialized incorrectly.
---

diff --git a/lib/isc/netmgr/tcpdns.c b/lib/isc/netmgr/tcpdns.c
index b06d56415da..aa2003ea795 100644
--- a/lib/isc/netmgr/tcpdns.c
+++ b/lib/isc/netmgr/tcpdns.c
@@ -98,7 +98,9 @@ dnstcp_readtimeout(uv_timer_t *timer) {
 	REQUIRE(sock->tid == isc_nm_tid());
 
 	/* Close the TCP connection; its closure should fire ours. */
-	isc_nmhandle_detach(&sock->outerhandle);
+	if (sock->outerhandle != NULL) {
+		isc_nmhandle_detach(&sock->outerhandle);
+	}
 }
 
 /*