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 923f9eb816c07d65d7c1c41499bb203fd46f5ab6..9b29e650b810bc5179e35964bbfa475ea1cdc483 100644 (file)
--- 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 53cfbcd206630491bd74c43212e4c55cce68781d..ba0499f7e048ef08b12b47ef33a1db04481c31d2 100644 (file)
--- 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;
     }
   }