[13] RFR: 8202414: Unsafe write after primitive array creation may result in array length change

[Rahul Raghavan]

Hi,

Please review the following fix proposal for JDK-8202414.

Webrev - http://cr.openjdk.java.net/~rraghavan/8202414/webrev.00/


-- Related links
 > https://bugs.openjdk.java.net/browse/JDK-8202414
 > 
http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2018-September/030536.html


-- As per suggestions in JBS added following change in 
InitializeNode::can_capture_store() to return false for unaligned stores.
=============
diff -r 3086f9259e97 src/hotspot/share/opto/memnode.cpp
--- a/src/hotspot/share/opto/memnode.cpp Wed Mar 13 00:48:52 2019 -0400
+++ b/src/hotspot/share/opto/memnode.cpp Wed Mar 13 19:50:07 2019 +0530
@@ -3541,7 +3541,7 @@
  // within the initialized memory.
  intptr_t InitializeNode::can_capture_store(StoreNode* st, 
PhaseTransform* phase, bool can_reshape) {
    const int FAIL = 0;
-  if (st->is_unaligned_access()) {
+  if (st->is_unaligned_access() || ((get_store_offset(st, phase) % 
BytesPerInt) != 0)) {
      return FAIL;
    }
    if (st->req() != MemNode::ValueIn + 1)
==============


-- Added the new jtreg test from the JBS unit test.
(test/hotspot/jtreg/compiler/c2/Test8202414.java)
Understood the test with unaligned access will not work for Sparc due to 
hardware restrictions.The test always fails with SIGBUS crash, with or 
without above fix. So added
    @requires (os.arch != "sparc") & (os.arch != "sparcv9")


-- Confirmed the above change solved the original reported 8202414 test 
case failure. Also no issues far for hs-tier1 to tier4, 
hs-precheckin-comp testing.

-- Could not work out any related additions in 
LibraryCallKit::inline_unsafe_access().
Hope above fix proposal is correct, complete solution for the issue.


Thanks,
Rahul