set async.done to TRUE last in the addrinfo callback to prevent the risk that

the multi-threaded resolver does wrong

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/hostasyn.c b/lib/hostasyn.c
index 2bf5a580a..5a0397d7a 100644
--- a/lib/hostasyn.c
+++ b/lib/hostasyn.c
@@ -115,7 +115,6 @@ static void addrinfo_callback(void *arg, /* "struct connectdata *" */
   struct connectdata *conn = (struct connectdata *)arg;
   struct Curl_dns_entry *dns = NULL;
 
-  conn->async.done = TRUE;
   conn->async.status = status;
 
   if(CURL_ASYNC_SUCCESS == status) {
@@ -147,6 +146,11 @@ static void addrinfo_callback(void *arg, /* "struct connectdata *" */
 
   conn->async.dns = dns;
 
+ /* Set async.done TRUE last in this function since it may be used multi-
+    threaded and once this is TRUE the other thread may read fields from the
+    async struct */
+  conn->async.done = TRUE;
+
   /* ipv4: The input hostent struct will be freed by ares when we return from
      this function */
 }