From deefc958c388995fac99c581284fb86eb9653ece Mon Sep 17 00:00:00 2001
From: Rainer Gerhards <rgerhards@adiscon.com>
Date: Thu, 23 Mar 2023 10:58:32 +0100
Subject: [PATCH] [backport] core/bugfix: using $uuid msg prop can deadlock
 rsyslog on shutdown

This problem can occur if a large number of threads is used and rsyslog
cannot shut down all queues etc within the regular time interval. In this
case, it cancels some threads. That can leave the mutex guarding libuuid
calls locked and thus prevents other, not yet cancelled threads from
progressing. Assuming pthread_mutex_lock() is not a cancellation point,
this will case these other threads to hang forever and thus create a
deadlock situation.

closes https://github.com/rsyslog/rsyslog/issues/5104

---

Conflict:NA
Type:bugfix
Reference:https://github.com/rsyslog/rsyslog/commit/82687e14fbf3d854e8cc954efb9fb0efa69a28d2

---
---
 runtime/msg.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/runtime/msg.c b/runtime/msg.c
index 73b7cec80..a3ddb8684 100644
--- a/runtime/msg.c
+++ b/runtime/msg.c
@@ -7,7 +7,7 @@
  * of the "old" message code without any modifications. However, it
  * helps to have things at the right place one we go to the meat of it.
  *
- * Copyright 2007-2022 Rainer Gerhards and Adiscon GmbH.
+ * Copyright 2007-2023 Rainer Gerhards and Adiscon GmbH.
  *
  * This file is part of the rsyslog runtime library.
  *
@@ -1618,13 +1618,22 @@ msgSetPRI(smsg_t *const __restrict__ pMsg, syslog_pri_t pri)
 /* note: libuuid seems not to be thread-safe, so we need
  * to get some safeguards in place.
  */
+static pthread_mutex_t mutUUID = PTHREAD_MUTEX_INITIALIZER;
+
+static void call_uuid_generate(uuid_t uuid)
+{
+	pthread_mutex_lock(&mutUUID);
+	pthread_cleanup_push(mutexCancelCleanup, &mutUUID);
+	uuid_generate(uuid);
+	pthread_cleanup_pop(1);
+}
+
 static void msgSetUUID(smsg_t * const pM)
 {
 	size_t lenRes = sizeof(uuid_t) * 2 + 1;
 	char hex_char [] = "0123456789ABCDEF";
 	unsigned int byte_nbr;
 	uuid_t uuid;
-	static pthread_mutex_t mutUUID = PTHREAD_MUTEX_INITIALIZER;
 
 	dbgprintf("[MsgSetUUID] START, lenRes %llu\n", (long long unsigned) lenRes);
 	assert(pM != NULL);
@@ -1632,9 +1641,7 @@ static void msgSetUUID(smsg_t * const pM)
 	if((pM->pszUUID = (uchar*) malloc(lenRes)) == NULL) {
 		pM->pszUUID = (uchar *)"";
 	} else {
-		pthread_mutex_lock(&mutUUID);
-		uuid_generate(uuid);
-		pthread_mutex_unlock(&mutUUID);
+		call_uuid_generate(uuid);
 		for (byte_nbr = 0; byte_nbr < sizeof (uuid_t); byte_nbr++) {
 			pM->pszUUID[byte_nbr * 2 + 0] = hex_char[uuid [byte_nbr] >> 4];
 			pM->pszUUID[byte_nbr * 2 + 1] = hex_char[uuid [byte_nbr] & 15];
@@ -5352,5 +5359,3 @@ BEGINObjClassInit(msg, 1, OBJ_IS_CORE_MODULE)
 	INIT_ATOMIC_HELPER_MUT(mutTrimCtr);
 #	endif
 ENDObjClassInit(msg)
-/* vim:set ai:
- */
-- 
2.12.3