From 5fe226b4378a2466d906ae45b8544f1003e9885a Mon Sep 17 00:00:00 2001
From: yefei25 <yefei25@huawei.com>
Date: Wed, 8 Apr 2020 23:10:58 -0400
Subject: [PATCH 1/2] check whether command_prev is null before assigning value

---
 src/core/service.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/core/service.c b/src/core/service.c
index 9a26271f72..3c255b3bcc 100644
--- a/src/core/service.c
+++ b/src/core/service.c
@@ -2569,12 +2569,16 @@ static unsigned service_exec_command_index(Unit *u, ServiceExecCommand id, ExecC
         assert(s);
         assert(id >= 0);
         assert(id < _SERVICE_EXEC_COMMAND_MAX);
-
+        if (!current)
+                return 0;
         first = s->exec_command[id];

         /* Figure out where we are in the list by walking back to the beginning */
-        for (c = current; c != first; c = c->command_prev)
+        for (c = current; c != first; c = c->command_prev) {
                 idx++;
+                if (!c->command_prev)
+                        return idx;
+        }

         return idx;
 }
--
2.19.1