[tomcat] branch 9.0.x updated: Fix possible concurrency issue

[markt]

This is an automated email from the ASF dual-hosted git repository.

markt pushed a commit to branch 9.0.x
in repository https://gitbox.apache.org/repos/asf/tomcat.git


The following commit(s) were added to refs/heads/9.0.x by this push:
     new a233ffd  Fix possible concurrency issue
a233ffd is described below

commit a233ffde7dd04165721d68f0ab9d9bac4b2ff90e
Author: Mark Thomas <ma...@apache.org>
AuthorDate: Tue Sep 15 17:34:50 2020 +0100

    Fix possible concurrency issue
---
 java/org/apache/coyote/http11/Http11InputBuffer.java | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/java/org/apache/coyote/http11/Http11InputBuffer.java 
b/java/org/apache/coyote/http11/Http11InputBuffer.java
index f5538af..9e5ffe0 100644
--- a/java/org/apache/coyote/http11/Http11InputBuffer.java
+++ b/java/org/apache/coyote/http11/Http11InputBuffer.java
@@ -71,7 +71,7 @@ public class Http11InputBuffer implements InputBuffer, 
ApplicationBufferHandler
     /**
      * State.
      */
-    private boolean parsingHeader;
+    private volatile boolean parsingHeader;
 
 
     /**
@@ -130,7 +130,7 @@ public class Http11InputBuffer implements InputBuffer, 
ApplicationBufferHandler
      */
     private byte prevChr = 0;
     private byte chr = 0;
-    private boolean parsingRequestLine;
+    private volatile boolean parsingRequestLine;
     private int parsingRequestLinePhase = 0;
     private boolean parsingRequestLineEol = false;
     private int parsingRequestLineStart = 0;
@@ -266,18 +266,22 @@ public class Http11InputBuffer implements InputBuffer, 
ApplicationBufferHandler
 
         byteBuffer.limit(0).position(0);
         lastActiveFilter = -1;
-        parsingHeader = true;
         swallowInput = true;
 
         chr = 0;
         prevChr = 0;
         headerParsePos = HeaderParsePosition.HEADER_START;
-        parsingRequestLine = true;
         parsingRequestLinePhase = 0;
         parsingRequestLineEol = false;
         parsingRequestLineStart = 0;
         parsingRequestLineQPos = -1;
         headerData.recycle();
+        // Recycled last because they are volatile
+        // All variables visible to this thread are guaranteed to be visible to
+        // any other thread once that thread reads the same volatile. The first
+        // action when parsing input data is to read one of these volatiles.
+        parsingRequestLine = true;
+        parsingHeader = true;
     }
 
 


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