Index: busybox-1.25.1/miscutils/lock.c
===================================================================
--- busybox-1.25.1.orig/miscutils/lock.c	2017-03-14 12:44:18.832516659 +0530
+++ busybox-1.25.1/miscutils/lock.c	2017-03-14 15:01:10.356577194 +0530
@@ -6,6 +6,7 @@
 #include <sys/types.h>
 #include <sys/file.h>
 #include <sys/stat.h>
+#include <sys/prctl.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <unistd.h>
@@ -69,6 +70,9 @@
 		}
 	}
 
+	/*to make sure that lock process exits if parent process is killed*/
+	prctl(PR_SET_PDEATHSIG, SIGKILL);
+
 	flags = shared ? LOCK_SH : LOCK_EX;
 	flags |= try_lock ? LOCK_NB : 0;