RFR: 8369393: NMT: poison the malloc header and footer under ASAN build [v2]

[Afshin Zafari]

On Wed, 17 Dec 2025 09:02:19 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> Under ASAN builds and when NMT is enabled, the header and footer of MallocHeader are poisoned/unpoisoned at malloc/realloc/free times.
>> Checking the integrity of memory blocks is off under ASAN builds.
>
> Afshin Zafari has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into asan_poison_malloc_hdr_ftr_v2
>  - removed extra newlines.
>  - fixes.
>  - inlining
>  - review comments applied.
>  - revision
>  - jtreg test excluded when ASAN is enabled.
>  - 8369393: NMT: poison the malloc header and footer under ASAN build

Dear @tstuefe, 
After your last comments on the previous version of this change, I have re-implemented the poisoning in a way aligned to your concerns. Please have a look and let me know if something is missed or can be improved. TIA

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PR Comment: https://git.openjdk.org/jdk/pull/28503#issuecomment-3759446359