From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Sat, 26 Oct 2019 16:47:49 +0000 (+0200)
Subject: dnsdist: Fix a race condition in the DOHUnit reference counter
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=241ec94c60b4c2169938d7214d5ee7ac11f86576;p=pdns

dnsdist: Fix a race condition in the DOHUnit reference counter

It was based on the reference counter used for the DOHAcceptContext
where thread safety was never an issue because those objects are
not shared between threads, but DOHUnit are.
---

diff --git a/pdns/dnsdistdist/doh.cc b/pdns/dnsdistdist/doh.cc
index 923f9eb81..9b29e650b 100644
--- a/pdns/dnsdistdist/doh.cc
+++ b/pdns/dnsdistdist/doh.cc
@@ -75,8 +75,7 @@ public:
 
   void release()
   {
-    --d_refcnt;
-    if (d_refcnt == 0) {
+    if (--d_refcnt == 0) {
       SSL_CTX_free(d_h2o_accept_ctx.ssl_ctx);
       d_h2o_accept_ctx.ssl_ctx = nullptr;
       delete this;
diff --git a/pdns/doh.hh b/pdns/doh.hh
index 53cfbcd20..ba0499f7e 100644
--- a/pdns/doh.hh
+++ b/pdns/doh.hh
@@ -151,8 +151,7 @@ struct DOHUnit
 
   void release()
   {
-    --d_refcnt;
-    if (d_refcnt == 0) {
+    if (--d_refcnt == 0) {
       delete this;
     }
   }