8187450: JNI local refs exceeds capacity warning in NetworkInterface::getAll

Reviewed-by: chegar, dfuchs, aph

Author: Jonathan Dowland

src/java.base/unix/native/libnet/NetworkInterface.c

@@ -503,6 +503,7 @@ JNIEXPORT jobjectArray JNICALL Java_java_net_NetworkInterface_getAll
 
         // put the NetworkInterface into the array
         (*env)->SetObjectArrayElement(env, netIFArr, arr_index++, netifObj);
+        (*env)->DeleteLocalRef(env, netifObj);
 
         curr = curr->next;
     }
@@ -766,12 +767,14 @@ static jobject createNetworkInterface(JNIEnv *env, netif *ifs) {
                             ((struct sockaddr_in*)addrP->brdcast)->sin_addr.s_addr));
                         JNU_CHECK_EXCEPTION_RETURN(env, NULL);
                         (*env)->SetObjectField(env, ibObj, ni_ib4broadcastID, ia2Obj);
+                        (*env)->DeleteLocalRef(env, ia2Obj);
                     } else {
                         return NULL;
                     }
                 }
                 (*env)->SetShortField(env, ibObj, ni_ib4maskID, addrP->mask);
                 (*env)->SetObjectArrayElement(env, bindArr, bind_index++, ibObj);
+                (*env)->DeleteLocalRef(env, ibObj);
             } else {
                 return NULL;
             }
@@ -800,12 +803,14 @@ static jobject createNetworkInterface(JNIEnv *env, netif *ifs) {
                 (*env)->SetObjectField(env, ibObj, ni_ibaddressID, iaObj);
                 (*env)->SetShortField(env, ibObj, ni_ib4maskID, addrP->mask);
                 (*env)->SetObjectArrayElement(env, bindArr, bind_index++, ibObj);
+                (*env)->DeleteLocalRef(env, ibObj);
             } else {
                 return NULL;
             }
         }
 
         (*env)->SetObjectArrayElement(env, addrArr, addr_index++, iaObj);
+        (*env)->DeleteLocalRef(env, iaObj);
         addrP = addrP->next;
     }
 
@@ -838,6 +843,11 @@ static jobject createNetworkInterface(JNIEnv *env, netif *ifs) {
     (*env)->SetObjectField(env, netifObj, ni_bindsID, bindArr);
     (*env)->SetObjectField(env, netifObj, ni_childsID, childArr);
 
+    (*env)->DeleteLocalRef(env, name);
+    (*env)->DeleteLocalRef(env, addrArr);
+    (*env)->DeleteLocalRef(env, bindArr);
+    (*env)->DeleteLocalRef(env, childArr);
+
     // return the NetworkInterface
     return netifObj;
 }

src/java.base/windows/native/libnet/NetworkInterface.c

@@ -641,8 +641,10 @@ jobject createNetworkInterface
                   return NULL;
               }
               (*env)->SetObjectField(env, ibObj, ni_ibbroadcastID, ia2Obj);
+              (*env)->DeleteLocalRef(env, ia2Obj);
               (*env)->SetShortField(env, ibObj, ni_ibmaskID, addrs->mask);
               (*env)->SetObjectArrayElement(env, bindsArr, bind_index++, ibObj);
+              (*env)->DeleteLocalRef(env, ibObj);
             }
         } else /* AF_INET6 */ {
             int scope;
@@ -667,16 +669,22 @@ jobject createNetworkInterface
                 (*env)->SetObjectField(env, ibObj, ni_ibaddressID, iaObj);
                 (*env)->SetShortField(env, ibObj, ni_ibmaskID, addrs->mask);
                 (*env)->SetObjectArrayElement(env, bindsArr, bind_index++, ibObj);
+                (*env)->DeleteLocalRef(env, ibObj);
             }
         }
         (*env)->SetObjectArrayElement(env, addrArr, addr_index, iaObj);
+        (*env)->DeleteLocalRef(env, iaObj);
         addrs = addrs->next;
         addr_index++;
     }
     (*env)->SetObjectField(env, netifObj, ni_addrsID, addrArr);
     (*env)->SetObjectField(env, netifObj, ni_bindsID, bindsArr);
 
     free_netaddr(netaddrP);
+    (*env)->DeleteLocalRef(env, name);
+    (*env)->DeleteLocalRef(env, displayName);
+    (*env)->DeleteLocalRef(env, addrArr);
+    (*env)->DeleteLocalRef(env, bindsArr);
 
     /*
      * Windows doesn't have virtual interfaces, so child array
@@ -687,6 +695,7 @@ jobject createNetworkInterface
       return NULL;
     }
     (*env)->SetObjectField(env, netifObj, ni_childsID, childArr);
+    (*env)->DeleteLocalRef(env, childArr);
 
     /* return the NetworkInterface */
     return netifObj;
@@ -959,6 +968,7 @@ JNIEXPORT jobjectArray JNICALL Java_java_net_NetworkInterface_getAll
 
         /* put the NetworkInterface into the array */
         (*env)->SetObjectArrayElement(env, netIFArr, arr_index++, netifObj);
+        (*env)->DeleteLocalRef(env, netifObj);
 
         curr = curr->next;
     }

test/jdk/java/net/NetworkInterface/Test.java

@@ -24,8 +24,8 @@
 /* @test
  * @bug 4405354 6594296 8058216
  * @library /test/lib
- * @run main Test
- * @run main/othervm -Djava.net.preferIPv4Stack=true Test
+ * @run main/othervm -Xcheck:jni Test
+ * @run main/othervm -Xcheck:jni -Djava.net.preferIPv4Stack=true Test
  * @summary Basic tests for NetworkInterface
  */
 import java.net.NetworkInterface;