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List:       openjdk-2d-dev
Subject:    [OpenJDK 2D-Dev] Potential problem in X11GraphicsDevice
From:       Dmitri.Trembovetski () Sun ! COM (Dmitri Trembovetski)
Date:       2009-03-25 22:32:13
Message-ID: 49CAB0ED.5080406 () Sun ! COM
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   Hi Roman,

   this issue was filed. While it's not very serious, and could at most be used 
to do a dos attack on one VM - but there's plenty of other ways to do that (like 
creating thousands of threads), it should still be addressed.

   Java security model won't allow the client code to be run in a privileged 
context, so there's no problem with the client trying to supply an object with 
overridden public methods which could potentially be called from JDK code with 
elevated privileges:


http://java.sun.com/javase/6/docs/technotes/guides/security/spec/security-spec.doc4.html#24646

When the checkPermission method of the AccessController is invoked by the most 
recent caller (e.g., a method in the File class), the basic algorithm for 
deciding whether to allow or deny the requested access is as follows.

If any caller in the call chain does not have the requested permission,
AccessControlException is thrown, unless the following is true --
a caller whose domain is granted the said permission has been marked as 
"privileged" (see the next section) and all parties subsequently called by
this caller (directly or indirectly) all have the said permission.

   Thanks,
     Dmitri

Roman Kennke wrote:
> Hi,
> 
> While looking through X11GraphicsDevice I found a potential problem. The
> array returned by getConfigurations() is the real thing, and is mutable.
> Client code could get the array and write crap into it (e.g. null). This
> will most likely turn out to be the problem of the caller in the end,
> but I'm not sure if it couldn't be used to do nasty things as well when
> sneaking in manipulated GC objects. Maybe this should be made so that it
> returns a copy of the real array instead?
> 
> /Roman


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