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Posted to dev@tomcat.apache.org by bu...@apache.org on 2014/07/29 09:28:44 UTC
[Bug 56784] New: Possible atomicity violations
https://issues.apache.org/bugzilla/show_bug.cgi?id=56784
Bug ID: 56784
Summary: Possible atomicity violations
Product: Tomcat 6
Version: 6.0.41
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P2
Component: Catalina
Assignee: dev@tomcat.apache.org
Reporter: diogogsousa@gmail.com
I'm developing a tool for atomicity violation detection and I think it have
found a few atomicity violations in catalina. These are issues are due to
non-atomic compositions of calls to a certain object.
In org.apache.catalina.core.ContainerBase, method getChildren(), lines
1526-1534:
> public ObjectName[] getChildren() {
> 1526: ObjectName result[]=new ObjectName[children.size()];
> Iterator it=children.values().iterator();
> int i=0;
> while( it.hasNext() ) {
> Object next=it.next();
> if( next instanceof ContainerBase ) {
> 1531: result[i++]=((ContainerBase)next).getJmxName();
> }
> }
> return result;
> }
Here "result" is alloced with size "children.size()". A concurrent thread may
add more objects to "children" possibly causing an invalid access to array
"result" in line 1531.
__
In org.apache.catalina.core.StandardEngine, method start(), lines 438-439:
> public void start() throws LifecycleException {
> ...
> 438: if( mserver.isRegistered(realmName ) ) {
> 439: mserver.invoke(realmName, "init",
> new Object[] {},
> new String[] {}
> );
> }
> ...
> }
Can the "init" method be unregistered between lines 438 and 439?
__
In org.apache.catalina.core.StandardContext, method addParameter(), lines
2659-2672:
> public void addParameter(String name, String value) {
> ...
> 2664: if (parameters.get(name) != null)
> throw new IllegalArgumentException
> (sm.getString("standardContext.parameter.duplicate", name));
>
> // Add this parameter to our defined set
> synchronized (parameters) {
> 2670: parameters.put(name, value);
> }
> fireContainerEvent("addParameter", name);
> }
A concurrent thread may add the same parameter between the execution of line
2664 and 2670. In that case both threads will think they succeeded, when the
expected behavior is for one of them to receive the exception thrown in line
2665.
Thank you
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[Bug 56784] Possible atomicity violations
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=56784
--- Comment #1 from Mark Thomas <ma...@apache.org> ---
(In reply to diogogsousa from comment #0)
> In org.apache.catalina.core.ContainerBase, method getChildren(), lines
> 1526-1534:
Technically this is valid although no-one has ever reported an issue. It is
likely that the error would only be seen by JMX clients and a refresh would fix
it. I'll get this fixed in 8.0.x for 8.0.11 onwards.
> In org.apache.catalina.core.StandardEngine, method start(), lines 438-439:
This only affects 6.0.x and I don't see any way for this to occur in normal (or
even fairly abnormal) usage. It is probably possible to trigger this if you try
really hard but I don't see a need for changes here.
> In org.apache.catalina.core.StandardContext, method addParameter(), lines
> 2659-2672:
Again this one is valid but no-one has reported an issue. I wouldn't expect to
see an issue in normal usage and concurrent threads configuring a Context would
be pretty unusual. A ConcurrentHashMap looks like it will be cleaner here so
I'll get that fixed in 8.0.x for 8.0.11 as well.
In terms of back-ports, given that we haven't had reports of any issues, I'm
leaning towards only fixing these in 8.0.x and not back-porting the changes to
earlier versions.
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[Bug 56784] Possible atomicity violations
Posted by bu...@apache.org.
https://issues.apache.org/bugzilla/show_bug.cgi?id=56784
Mark Thomas <ma...@apache.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #2 from Mark Thomas <ma...@apache.org> ---
Fixes applied to 8.0.x as discussed for 8.0.11 onwards.
I do not plan on back-porting them.
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