RFR: 8346866: [ASAN] memoryReserver.cpp reported applying non-zero offset to non-null pointer produced null pointer [v2]

[SendaoYan]

On Thu, 2 Jan 2025 08:31:57 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> SendaoYan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add "attach_point <= stepsize" check at the end of for loop, to make sanitizer silent and avoid warp around.
>
> src/hotspot/share/memory/memoryReserver.cpp line 440:
> 
>> 438:   // Try attach points from top to bottom.
>> 439:   for (char* attach_point = highest_start;
>> 440:        attach_point >= lowest_start;  // Avoid wrap around.
> 
> The comment is no longer true or relevant.  That comment was about the clause that is being removed.

The unrelevant comment has been removed.

> src/hotspot/share/memory/memoryReserver.cpp line 455:
> 
>> 453: 
>> 454:     if (p2u(attach_point) <= stepsize)
>> 455:       break;  // Make sanizier silent and avoid warp around.
> 
> Sanitizer isn't interesting.  The point is this avoids pointer underflow.  Also, braces are required for multiline
> `if` statements - see style guide.

Thanks @kimbarrett, the comment has been updated, and the braces has been added.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22897#discussion_r1900673469
PR Review Comment: https://git.openjdk.org/jdk/pull/22897#discussion_r1900674391