From 82845f8d045a1fdbac17cf1959ad51906a8840ed Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 27 Sep 2019 11:59:58 +0200
Subject: [PATCH] TerminateModuleForkChild(): use wait4 for safety.

In theory currently there is only one active child, but the API may
change or for bugs in the implementation we may have several (it was
like that for years because of a bug). Better to wait for a specific
pid and avoid consuing other pending children information.
---
 src/module.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/module.c b/src/module.c
index d3b37a3d8..cee7a85a9 100644
--- a/src/module.c
+++ b/src/module.c
@@ -5193,7 +5193,8 @@ void TerminateModuleForkChild(int wait) {
     serverLog(LL_NOTICE,"Killing running module fork child: %ld",
         (long) server.module_child_pid);
     if (kill(server.module_child_pid,SIGUSR1) != -1 && wait) {
-        while(wait3(&statloc,0,NULL) != server.module_child_pid);
+        while(wait4(server.module_child_pid,&statloc,0,NULL) !=
+              server.module_child_pid);
     }
     /* Reset the buffer accumulating changes while the child saves. */
     server.module_child_pid = -1;