mqtt: clear the leftovers pointer when sending succeeds

CVE-2021-22945

Bug: https://curl.se/docs/CVE-2021-22945.html

diff --git a/lib/mqtt.c b/lib/mqtt.c
index f077e6c3dc44207afa80cca68fa6c4ee1032d6dd..fcd40b41e600e77ed71b93b7bcf1813c79044cce 100644 (file)
--- a/lib/mqtt.c
+++ b/lib/mqtt.c
@@ -128,6 +128,10 @@ static CURLcode mqtt_send(struct Curl_easy *data,
     mq->sendleftovers = sendleftovers;
     mq->nsend = nsend;
   }
+  else {
+    mq->sendleftovers = NULL;
+    mq->nsend = 0;
+  }
   return result;
 }