Race condition fix for findThunkFromTerseSignature #3073
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match points to an entry inside a TR_PersistentArray in TR_J2IThunkTable. Before returning from findThunkFromTerseSignature, the code attempts to read from match->_thunk after leaving the critical section. This is bad because if the TR_PersistentArray grows, the match pointer is stale and may not point to the correct entry anymore. This fix moves the read from match->_thunk into the critical section. Assuming locking is handled properly in other areas, this will prevent the match pointer from going stale unexpectedly and ensures a valid match->_thunk. Issue: eclipse-openj9#3006 Signed-off-by: jimmyk <jimmyk@ca.ibm.com>
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@gita-omr - @andrewcraik is travelling this weekend, can anyone else review this? @mstoodle @vijaysun-omr @0xdaryl @fjeremic @zl-wang ? |
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@pshipton FYI |
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@IBMJimmyk fyi you can use a keyword to auto-close the issue when the PR gets merged. I've already changed it. |
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Jenkins test sanity |
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@IBMJimmyk : the WIP will have to be removed before this is merged. The proposed fix looks reasonable to me. |
mpirvu
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Sep 29, 2018
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jenkins test sanity all jdk11 |
pshipton
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Pretty sure Gita meant to merge this and not close it. |
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match points to an entry inside a TR_PersistentArray in TR_J2IThunkTable.
Before returning from findThunkFromTerseSignature, the code attempts to
read from match->_thunk after leaving the critical section. This is bad
because if the TR_PersistentArray grows, the match pointer is stale and
may not point to the correct entry anymore.
This fix moves the read from match->_thunk into the critical section.
Assuming locking is handled properly in other areas, this will prevent the
match pointer from going stale unexpectedly and ensures a valid
match->_thunk.
Fixes: #3006
Signed-off-by: jimmyk jimmyk@ca.ibm.com