From 57ab828ba10b5fdc3dbc11e7b38a6b3ff1bea42c Mon Sep 17 00:00:00 2001
From: Max Lv <max.c.lv@gmail.com>
Date: Wed, 27 Dec 2017 21:43:28 -0800
Subject: [PATCH] Fix a potential null pointer acceess issue. #1854

It's possible that c-ares calls the callback function immediately in ares_gethostbyname, which may free the server
structure in that callback function.
---
 src/server.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/server.c b/src/server.c
index be7db43f..4aa2a237 100644
--- a/src/server.c
+++ b/src/server.c
@@ -903,6 +903,8 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
                 ev_io_start(EV_A_ & remote->send_ctx->io);
             }
         } else {
+            ev_io_stop(EV_A_ & server_recv_ctx->io);
+
             query_t *query = ss_malloc(sizeof(query_t));
             memset(query, 0, sizeof(query_t));
             query->server = server;
@@ -920,8 +922,6 @@ server_recv_cb(EV_P_ ev_io *w, int revents)
                 close_and_free_server(EV_A_ server);
                 return;
             }
-
-            ev_io_stop(EV_A_ & server_recv_ctx->io);
         }
 
         return;