RFR: 8369393: NMT: poison the canaries of malloc header under ASAN build [v20]

[Johan Sjölen]

On Mon, 10 Nov 2025 08:46:41 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> NMT can detect malloc'd memory corruption using canary tests at header and footer of every memory region. This can only be done at free time of the memory where NNT checks the canaries and report error if they are not as expected.
>> In this PR, the canary parts also are poisoned using ASAN API to get notified whenever a read/write op is done. on the canary parts. `_size` member of the malloc header is also poisoned, since it is used for finding the footer address.
>
> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
> 
>   order of includes corrected.

Marked as reviewed by jsjolen (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27685#pullrequestreview-3441756471