From: Tony Finch <fanf@isc.org>
Date: Thu, 30 Mar 2023 16:56:08 +0000 (+0100)
Subject: Fix a crash when dig or host receive a signal
X-Git-Tag: v9.19.12~45^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=194621a74eaaa5834533a1602078112916fdabe6;p=thirdparty%2Fbind9.git

Fix a crash when dig or host receive a signal

When the loopmanager is shutting down following a signal,
`dig` and `host` should stop cleanly. Before this commit
they were oblivious to ISC_R_SHUTTINGDOWN.

The `isc_signal` callbacks now report this kind of mistake
with a stack backtrace.
---

diff --git a/CHANGES b/CHANGES
index 211adb7403b..3a35753cdb0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+6134.	[bug]		Fix a crash when dig or host receive a signal.
+			[GL #3970]
+
 6133.	[cleanup]	Refactor the isc_job_run() to not make any allocations
 			by embedding isc_job_t into callback argument, and
 			running it directly.  As a side-effect, isc_async_run
diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index 97b53f1b2fa..e36023e2989 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -3911,7 +3911,9 @@ recv_done(isc_nmhandle_t *handle, isc_result_t eresult, isc_region_t *region,
 
 	lookup_attach(query->lookup, &l);
 
-	if (eresult == ISC_R_CANCELED || query->canceled) {
+	if (eresult == ISC_R_CANCELED || eresult == ISC_R_SHUTTINGDOWN ||
+	    query->canceled)
+	{
 		debug("recv_done: cancel");
 		isc_nmhandle_detach(&query->readhandle);
 		if (!query->canceled) {
diff --git a/lib/isc/loop_p.h b/lib/isc/loop_p.h
index 8810a366197..9594a0f306a 100644
--- a/lib/isc/loop_p.h
+++ b/lib/isc/loop_p.h
@@ -121,7 +121,11 @@ struct isc_loopmgr {
 /*
  * Signal Handler
  */
+#define SIGNAL_MAGIC	ISC_MAGIC('S', 'I', 'G', ' ')
+#define VALID_SIGNAL(t) ISC_MAGIC_VALID(t, SIGNAL_MAGIC)
+
 struct isc_signal {
+	int magic;
 	uv_signal_t signal;
 	isc_loop_t *loop;
 	isc_signal_cb cb;
diff --git a/lib/isc/signal.c b/lib/isc/signal.c
index 69c75412889..5181f15af18 100644
--- a/lib/isc/signal.c
+++ b/lib/isc/signal.c
@@ -30,6 +30,7 @@ isc_signal_new(isc_loopmgr_t *loopmgr, isc_signal_cb cb, void *cbarg,
 
 	signal = isc_mem_get(isc_loop_getmctx(loop), sizeof(*signal));
 	*signal = (isc_signal_t){
+		.magic = SIGNAL_MAGIC,
 		.cb = cb,
 		.cbarg = cbarg,
 		.signum = signum,
@@ -48,18 +49,22 @@ isc_signal_new(isc_loopmgr_t *loopmgr, isc_signal_cb cb, void *cbarg,
 static void
 isc__signal_destroy_cb(uv_handle_t *handle) {
 	isc_signal_t *signal = uv_handle_get_data(handle);
-	isc_loop_t *loop = signal->loop;
+	isc_loop_t *loop = NULL;
 
-	isc_mem_put(loop->mctx, signal, sizeof(*signal));
+	REQUIRE(VALID_SIGNAL(signal));
 
+	loop = signal->loop;
+	isc_mem_put(loop->mctx, signal, sizeof(*signal));
 	isc_loop_detach(&loop);
 }
 
 void
 isc_signal_destroy(isc_signal_t **signalp) {
-	isc_signal_t *signal;
+	isc_signal_t *signal = NULL;
+
+	REQUIRE(signalp != NULL);
+	REQUIRE(VALID_SIGNAL(*signalp));
 
-	REQUIRE(signalp != NULL && *signalp != NULL);
 	signal = *signalp;
 	*signalp = NULL;
 
@@ -68,7 +73,10 @@ isc_signal_destroy(isc_signal_t **signalp) {
 
 void
 isc_signal_stop(isc_signal_t *signal) {
-	int r = uv_signal_stop(&signal->signal);
+	int r;
+
+	REQUIRE(VALID_SIGNAL(signal));
+	r = uv_signal_stop(&signal->signal);
 	UV_RUNTIME_CHECK(uv_signal_stop, r);
 }
 
@@ -76,6 +84,7 @@ static void
 isc__signal_cb(uv_signal_t *handle, int signum) {
 	isc_signal_t *signal = uv_handle_get_data((uv_handle_t *)handle);
 
+	REQUIRE(VALID_SIGNAL(signal));
 	REQUIRE(signum == signal->signum);
 
 	signal->cb(signal->cbarg, signum);
@@ -83,7 +92,9 @@ isc__signal_cb(uv_signal_t *handle, int signum) {
 
 void
 isc_signal_start(isc_signal_t *signal) {
-	int r = uv_signal_start(&signal->signal, isc__signal_cb,
-				signal->signum);
+	int r;
+
+	REQUIRE(VALID_SIGNAL(signal));
+	r = uv_signal_start(&signal->signal, isc__signal_cb, signal->signum);
 	UV_RUNTIME_CHECK(uv_signal_start, r);
 }