From d1d8f6bacb489036d0fd479c9dd3c0102c988889 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sun, 14 Aug 2022 21:28:32 +0100
Subject: [PATCH] patch 9.0.0211: invalid memory access when compiling :lockvar

Problem:    Invalid memory access when compiling :lockvar.
Solution:   Don't read past the end of the line.
---

diff --git a/src/vim9cmds.c b/src/vim9cmds.c
index ad32c32ff7cb..35a382138bf3 100644
--- a/src/vim9cmds.c
+++ b/src/vim9cmds.c
@@ -188,10 +188,17 @@ compile_lock_unlock(
     size_t	len;
     char_u	*buf;
     isntype_T	isn = ISN_EXEC;
+    char	*cmd = eap->cmdidx == CMD_lockvar ? "lockvar" : "unlockvar";
 
     if (cctx->ctx_skip == SKIP_YES)
 	return OK;
 
+    if (*p == NUL)
+    {
+	semsg(_(e_argument_required_for_str), cmd);
+	return FAIL;
+    }
+
     // Cannot use :lockvar and :unlockvar on local variables.
     if (p[1] != ':')
     {
@@ -223,8 +230,6 @@ compile_lock_unlock(
 	ret = FAIL;
     else
     {
-	char *cmd = eap->cmdidx == CMD_lockvar ? "lockvar" : "unlockvar";
-
 	if (deep < 0)
 	    vim_snprintf((char *)buf, len, "%s! %s", cmd, p);
 	else