commit 8019e88dd1ac73a3baa71e9acfbc1b7a3fbc7442
Author: Willy Tarreau <w@1wt.eu>
Date:   Tue Oct 16 17:37:12 2018 +0200

    BUILD: lua: silence some compiler warnings about potential null derefs (#2)
    
    Here we make sure that appctx is always taken from the unchecked value
    since we know it's an appctx, which explains why it's immediately
    dereferenced. A missing test was added to ensure that task_new() does
    not return a NULL.
    
    This may be backported to 1.8.
    
    (cherry picked from commit e09101e8d92b0c0ef8674fbc791e309112ab7f1c)
    Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/src/hlua.c b/src/hlua.c
index 64102e8a..ad9238ef 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -2361,7 +2361,7 @@ __LJMP static int hlua_socket_connect_yield(struct lua_State *L, int status, lua
 		return 2;
 	}
 
-	appctx = objt_appctx(s->si[0].end);
+	appctx = __objt_appctx(s->si[0].end);
 
 	/* Check for connection established. */
 	if (appctx->ctx.hlua_cosocket.connected) {
@@ -2473,7 +2473,7 @@ __LJMP static int hlua_socket_connect(struct lua_State *L)
 	}
 
 	hlua = hlua_gethlua(L);
-	appctx = objt_appctx(s->si[0].end);
+	appctx = __objt_appctx(s->si[0].end);
 
 	/* inform the stream that we want to be notified whenever the
 	 * connection completes.
@@ -5693,6 +5693,9 @@ static int hlua_register_task(lua_State *L)
 		WILL_LJMP(luaL_error(L, "lua out of memory error."));
 
 	task = task_new(MAX_THREADS_MASK);
+	if (!task)
+		WILL_LJMP(luaL_error(L, "Lua out of memory error."));
+
 	task->context = hlua;
 	task->process = hlua_process_task;