From 79a1c19ac28ae7feb23630507c2c192e84ba2cb7 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Sun, 17 Jun 2018 10:44:01 +0200
Subject: [PATCH] XADD MAXLEN should return an error for values < 0.

---
 src/t_stream.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/t_stream.c b/src/t_stream.c
index bcef4355..20daeee9 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -1105,6 +1105,11 @@ void xaddCommand(client *c) {
             }
             if (getLongLongFromObjectOrReply(c,c->argv[i+1],&maxlen,NULL)
                 != C_OK) return;
+
+            if (maxlen < 0) {
+                addReplyError(c,"The MAXLEN argument must be equal or greater than zero. A value of zero means that no trimming should be performed.");
+                return;
+            }
             i++;
             maxlen_arg_idx = i;
         } else {