From 6b67f8ec81b4811dbad35c982c51e769eda67133 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Thu, 5 Mar 2015 14:14:19 +0100
Subject: [PATCH] Fix possible AttributeMap corruption on double removal

Motivation:

When remove0() is called multiple times for an DefaultAttribute it can cause corruption of the internal linked-list structure.

Modifications:

- Ensure remove0() can not cause corruption by null out prev and next references.

Result:

No more corruption possible
---
 common/src/main/java/io/netty/util/DefaultAttributeMap.java | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/common/src/main/java/io/netty/util/DefaultAttributeMap.java b/common/src/main/java/io/netty/util/DefaultAttributeMap.java
index 2cd6d4a9e9..f136e232e5 100644
--- a/common/src/main/java/io/netty/util/DefaultAttributeMap.java
+++ b/common/src/main/java/io/netty/util/DefaultAttributeMap.java
@@ -172,6 +172,11 @@ public class DefaultAttributeMap implements AttributeMap {
                     if (next != null) {
                         next.prev = prev;
                     }
+
+                    // Null out prev and next - this will guard against multiple remove0() calls which may corrupt
+                    // the linked list for the bucket.
+                    prev = null;
+                    next = null;
                 }
             }
         }