[UNDERTOW-2298] Avoid NPE on concurrent close/timeout

Author: baranowb

servlet/src/main/java/io/undertow/servlet/UndertowServletLogger.java

@@ -32,6 +32,7 @@
 
 import static org.jboss.logging.Logger.Level.ERROR;
 import static org.jboss.logging.Logger.Level.WARN;
+import static org.jboss.logging.Logger.Level.TRACE;
 
 /**
  * log messages start at 15000
@@ -140,4 +141,7 @@ public interface UndertowServletLogger extends BasicLogger {
     @Message(id = 15024, value = "Servlet %s init() method in web application %s threw exception")
     void failedToLoad(String servletName, String appName, @Cause Throwable t);
 
+    @LogMessage(level = TRACE)
+    @Message(id = 15025, value = "IO Operation de-synchronization trace: ")
+    void ioOperationDesynchronization( @Cause Throwable t);
 }

servlet/src/main/java/io/undertow/servlet/spec/ServletInputStreamImpl.java

@@ -35,6 +35,7 @@
 import org.xnio.channels.StreamSourceChannel;
 import io.undertow.connector.ByteBufferPool;
 import io.undertow.connector.PooledByteBuffer;
+import io.undertow.servlet.UndertowServletLogger;
 import io.undertow.servlet.UndertowServletMessages;
 
 /**
@@ -196,14 +197,21 @@ public int read(final byte[] b, final int off, final int len) throws IOException
 
     private void readIntoBuffer() throws IOException {
         if (pooled == null && !anyAreSet(state, FLAG_FINISHED)) {
-            pooled = bufferPool.allocate();
+             try {
+                pooled = bufferPool.allocate();
 
-            int res = Channels.readBlocking(channel, pooled.getBuffer());
-            pooled.getBuffer().flip();
-            if (res == -1) {
-                setFlags(FLAG_FINISHED);
-                pooled.close();
-                pooled = null;
+                int res = Channels.readBlocking(channel, pooled.getBuffer());
+                pooled.getBuffer().flip();
+                if (res == -1) {
+                    setFlags(FLAG_FINISHED);
+                    pooled.close();
+                    pooled = null;
+                }
+            } catch(NullPointerException npe) {
+                //UNDERTOW-2298 - this will happen in small window when read is happening and timeout happens
+                if(!isFinished()) {
+                    UndertowServletLogger.ROOT_LOGGER.ioOperationDesynchronization(npe);
+                }
             }
         }
     }

spotbugs-exclude.xml

@@ -932,4 +932,9 @@
     <Match>
         <Package name="io.undertow.benchmarks"/>
     </Match>
+    <Match>
+        <Bug pattern="DCN_NULLPOINTER_EXCEPTION"/>
+        <Class name="io.undertow.servlet.spec.ServletInputStreamImpl"/>
+        <Method name="readIntoBuffer"/>
+    </Match>
 </FindBugsFilter>