Jacek Caban : rpcrt4: Always protect ref access for connections associated with protseq in RPCRT4_ReleaseConnection.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 2d9e894d285937716a4541c7fab9152fdf0b495f
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=2d9e894d285937716a4541c7fab9152fdf0b495f

Author: Jacek Caban <jacek at codeweavers.com>
Date:   Wed Aug  2 15:51:09 2017 +0200

rpcrt4: Always protect ref access for connections associated with protseq in RPCRT4_ReleaseConnection.

Signed-off-by: Jacek Caban <jacek at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/rpcrt4/rpc_transport.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/dlls/rpcrt4/rpc_transport.c b/dlls/rpcrt4/rpc_transport.c
index 48def49..5735b0f 100644
--- a/dlls/rpcrt4/rpc_transport.c
+++ b/dlls/rpcrt4/rpc_transport.c
@@ -3382,20 +3382,24 @@ RpcConnection *RPCRT4_GrabConnection(RpcConnection *connection)
 
 void RPCRT4_ReleaseConnection(RpcConnection *connection)
 {
-    LONG ref = InterlockedDecrement(&connection->ref);
+    LONG ref;
 
-    if (!ref && connection->protseq)
+    /* protseq stores a list of active connections, but does not own references to them.
+     * It may need to grab a connection from the list, which could lead to a race if
+     * connection is being released, but not yet removed from the list. We handle that
+     * by synchronizing on CS here. */
+    if (connection->protseq)
     {
-        /* protseq stores a list of active connections, but does not own references to them.
-         * It may need to grab a connection from the list, which could lead to a race if
-         * connection is being released, but not yet removed from the list. We handle that
-         * by synchronizing on CS here. */
         EnterCriticalSection(&connection->protseq->cs);
-        ref = connection->ref;
+        ref = InterlockedDecrement(&connection->ref);
         if (!ref)
             list_remove(&connection->protseq_entry);
         LeaveCriticalSection(&connection->protseq->cs);
     }
+    else
+    {
+        ref = InterlockedDecrement(&connection->ref);
+    }
 
     TRACE("%p ref=%u\n", connection, ref);