From 61b5792340197b38b7fb4be7168835c429bd5315 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Tue, 24 Nov 2015 04:54:39 +0100
Subject: [PATCH] Fix race-condition when closing a NioSocketChannel or
 EpollSocketChannel

Motivation:

Fix a race-condition when closing NioSocketChannel or EpollSocketChannel while try to detect if a close executor should be used and the underlying socket was already closed. This could lead to an exception that then leave the channel / in an invalid state and so could lead to side-effects like heavy CPU usage.

Modifications:

Catch possible socket exception while try to get the SO_LINGER options from the underlying socket.

Result:

No more race-condition when closing the channel is possible with bad side-effects.
---
 .../io/netty/channel/epoll/EpollSocketChannel.java | 14 ++++++++++----
 .../netty/channel/socket/nio/NioSocketChannel.java | 11 +++++++++--
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java
index 72a2b6ae1b..ec14d4aec7 100644
--- a/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java
+++ b/transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java
@@ -219,10 +219,16 @@ public final class EpollSocketChannel extends AbstractEpollStreamChannel impleme
     private final class EpollSocketChannelUnsafe extends EpollStreamUnsafe {
         @Override
         protected Executor closeExecutor() {
-            // Check isOpen() first as otherwise it will throw a RuntimeException
-            // when call getSoLinger() as the fd is not valid anymore.
-            if (isOpen() && config().getSoLinger() > 0) {
-                return GlobalEventExecutor.INSTANCE;
+            try {
+                // Check isOpen() first as otherwise it will throw a RuntimeException
+                // when call getSoLinger() as the fd is not valid anymore.
+                if (isOpen() && config().getSoLinger() > 0) {
+                    return GlobalEventExecutor.INSTANCE;
+                }
+            } catch (Throwable ignore) {
+                // Ignore the error as the underlying channel may be closed in the meantime and so
+                // getSoLinger() may produce an exception. In this case we just return null.
+                // See https://github.com/netty/netty/issues/4449
             }
             return null;
         }
diff --git a/transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java b/transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java
index 5d7aa121ba..af2520d96e 100644
--- a/transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java
+++ b/transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java
@@ -35,6 +35,7 @@ import java.io.IOException;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.net.SocketAddress;
+import java.net.SocketException;
 import java.nio.ByteBuffer;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
@@ -333,8 +334,14 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
     private final class NioSocketChannelUnsafe extends NioByteUnsafe {
         @Override
         protected Executor closeExecutor() {
-            if (javaChannel().isOpen() && config().getSoLinger() > 0) {
-                return GlobalEventExecutor.INSTANCE;
+            try {
+                if (javaChannel().isOpen() && config().getSoLinger() > 0) {
+                    return GlobalEventExecutor.INSTANCE;
+                }
+            } catch (Throwable ignore) {
+                // Ignore the error as the underlying channel may be closed in the meantime and so
+                // getSoLinger() may produce an exception. In this case we just return null.
+                // See https://github.com/netty/netty/issues/4449
             }
             return null;
         }