8129957: Deadlock in JNDI LDAP implementation when closing the LDAP context

Reviewed-by: vinnie

src/share/classes/com/sun/jndi/ldap/LdapClient.java

@@ -494,7 +494,6 @@ public final class LdapClient implements PooledConnection {
      */
     void processConnectionClosure() {
         // Notify listeners
-        synchronized (unsolicited) {
         if (unsolicited.size() > 0) {
             String msg;
             if (conn != null) {
@@ -504,7 +503,6 @@ public final class LdapClient implements PooledConnection {
             }
             notifyUnsolicited(new CommunicationException(msg));
         }
-        }
 
         // Remove from pool
         if (pooled) {
@@ -1499,13 +1497,8 @@ public final class LdapClient implements PooledConnection {
         if (debug > 0) {
             System.err.println("LdapClient.removeUnsolicited" + ctx);
         }
-        synchronized (unsolicited) {
-            if (unsolicited.size() == 0) {
-                return;
-            }
             unsolicited.removeElement(ctx);
         }
-    }
 
     // NOTE: Cannot be synchronized because this is called asynchronously
     // by the reader thread in Connection. Instead, sync on 'unsolicited' Vector.
@@ -1513,7 +1506,6 @@ public final class LdapClient implements PooledConnection {
         if (debug > 0) {
             System.err.println("LdapClient.processUnsolicited");
         }
-        synchronized (unsolicited) {
         try {
             // Parse the response
             LdapResult res = new LdapResult();
@@ -1532,11 +1524,17 @@ public final class LdapClient implements PooledConnection {
                 forceClose(pooled);
             }
 
+            LdapCtx first = null;
+            UnsolicitedNotification notice = null;
+
+            synchronized (unsolicited) {
                 if (unsolicited.size() > 0) {
+                    first = unsolicited.elementAt(0);
+
                     // Create an UnsolicitedNotification using the parsed data
                     // Need a 'ctx' object because we want to use the context's
                     // list of provider control factories.
-                    UnsolicitedNotification notice = new UnsolicitedResponseImpl(
+                    notice = new UnsolicitedResponseImpl(
                         res.extensionId,
                         res.extensionValue,
                         res.referrals,
@@ -1544,9 +1542,12 @@ public final class LdapClient implements PooledConnection {
                         res.errorMessage,
                         res.matchedDN,
                         (res.resControls != null) ?
-                        unsolicited.elementAt(0).convertControls(res.resControls) :
+                        first.convertControls(res.resControls) :
                         null);
+                }
+            }
 
+            if (notice != null) {
                 // Fire UnsolicitedNotification events to listeners
                 notifyUnsolicited(notice);
 
@@ -1558,9 +1559,6 @@ public final class LdapClient implements PooledConnection {
                 }
             }
         } catch (IOException e) {
-                if (unsolicited.size() == 0)
-                    return;  // no one registered; ignore
-
             NamingException ne = new CommunicationException(
                 "Problem parsing unsolicited notification");
             ne.setRootCause(e);
@@ -1571,17 +1569,20 @@ public final class LdapClient implements PooledConnection {
             notifyUnsolicited(e);
         }
     }
-    }
 
 
     private void notifyUnsolicited(Object e) {
-        for (int i = 0; i < unsolicited.size(); i++) {
-            unsolicited.elementAt(i).fireUnsolicited(e);
-        }
+        Vector<LdapCtx> unsolicitedCopy;
+        synchronized (unsolicited) {
+            unsolicitedCopy = new Vector<>(unsolicited);
             if (e instanceof NamingException) {
                 unsolicited.setSize(0);  // no more listeners after exception
             }
         }
+        for (int i = 0; i < unsolicitedCopy.size(); i++) {
+            unsolicitedCopy.elementAt(i).fireUnsolicited(e);
+        }
+    }
 
     private void ensureOpen() throws IOException {
         if (conn == null || !conn.useable) {