Improve robustness of checking tags of allocated memory blocks #4191
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J9MemTag.allocSize has type uintptr_t (aka UDATA), which is mapped to U64 by MSVC on Windows (or with the changes in eclipse-omr/omr#3355 on all 64-bit platforms). A random address treated as a pointer to a J9MemTag has a 50% chance of referring to a J9MemTag where allocSize >= 2^63 which would trigger an InvalidDataTypeException from U64.longValue(). This change modifies ROUNDED_FOOTER_OFFSET() so it always returns a UDATA object independent of the actual argument type, thus avoiding that exception for blocks that otherwise would fail the sanity checks. Signed-off-by: Keith W. Campbell <keithc@ca.ibm.com>
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Jenkins test all zlinux jdk11 depends eclipse-omr/omr#3422 |
DanHeidinga
reviewed
Jan 7, 2019
debugtools/DDR_VM/src/com/ibm/j9ddr/vm29/pointer/helper/J9MemTagHelper.java
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Jenkins test all win jdk11 depends eclipse-omr/omr#3422 |
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jenkins test sanity win jdk11 depends eclipse-omr/omr#3422 |
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jenkins test extended win jdk11 depends eclipse-omr/omr#3422 |
pshipton
approved these changes
Jan 8, 2019
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J9MemTag.allocSize has type uintptr_t (aka UDATA), which is mapped to U64 by MSVC on Windows (or with the changes in eclipse-omr/omr#3355 on all 64-bit platforms). A random address treated as a pointer to a J9MemTag has a 50% chance of referring to a J9MemTag where allocSize >= 2^63 which would trigger an InvalidDataTypeException from U64.longValue(). This change modifies ROUNDED_FOOTER_OFFSET() so it always returns a UDATA object independent of the actual
argument type, thus avoiding that exception for blocks that otherwise would fail the sanity checks.
eclipse-omr/omr#3422 replays eclipse-omr/omr#3355.