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copied!<p>Here we are faced with a bug in the JIT-compiler. Compiler determines that the allocated array is filled after allocation in <code>Arrays.fill(...)</code>, but the check for uses between the allocation and the fill is faulty. So, compiler performs an illegal optimization - it skips zeroing of allocated array.</p> <p>This bug is placed in Oracle bug tracker (<a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7196857">bug id 7196857</a>). Unfortunately, I did not wait for any clarifications from Oracle about the following points. As I see, this bug is OS-specific: it absolutely reproducible on 64-bit Linux and Mac, but, as I see from comments, it reproduces not regularly on Windows (for similar versions of JDK). Additionally it would be nice to know when this bug will be fixed.</p> <p>There is only advice at the moment: do not use JDK1.7.0_04 or later if you depend on JLS for newly declared arrays.</p> <p><em>Update at October 5:</em></p> <p>In the new <a href="http://jdk7.java.net/download.html">Build 10</a> of the JDK 7u10 (early access) released at October 04, 2012, this bug was fixed at least for Linux OS (I did not test for other). Thanks to @Makoto, who found that this bug is no longer available for public access in Oracle bug database. Unfortunately, I do not know for the reasons Oracle removed it from public access, but it is available in Google <a href="http://webcache.googleusercontent.com/search?q=cache%3aQ0V_rKQNw5sJ%3abugs.sun.com/bugdatabase/view_bug.do?bug_id=7196857%20&cd=5&hl=en&ct=clnk">cache</a>. Also, this bug has caught the attention of Redhat: the CVE identifiers <a href="https://access.redhat.com/security/cve/CVE-2012-4420">CVE-2012-4420</a> (<a href="https://bugzilla.redhat.com/show_bug.cgi?id=856588">bugzilla</a>) and <a href="https://access.redhat.com/security/cve/CVE-2012-4416">CVE-2012-4416</a> (<a href="https://bugzilla.redhat.com/show_bug.cgi?id=856124">bugzilla</a>) were assigned to this flaw.</p>

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