Integrated: 8346714: [ASAN] compressedKlass.cpp reported applying non-zero offset to null pointer

[SendaoYan]

On Fri, 20 Dec 2024 12:56:08 GMT, SendaoYan <syan at openjdk.org> wrote:

> Hi all,
> CompressedKlassPointers::sanity_check_after_initialization() src/hotspot/share/oops/compressedKlass.cpp:104:38 reported runtime error: applying non-zero offset 4294967296 to null pointer by clang17 UndefinedBehaviorSanitizer.
> 
> The _base initial as nullptr in function CompressedKlassPointers::initialize(address addr, size_t len) shows as below. In C/C++, offsetting a null pointer is undefined behavior. This PR do not change the original logic but eliminate the undefined behaviour in code, the risk is low.
> 
> ```c++
>     address const end = addr + len;
>     if (end <= (address)unscaled_max) {
>       _base = nullptr;
>       _shift = 0;

This pull request has now been integrated.

Changeset: bffa77bc
Author:    SendaoYan <syan at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/bffa77bc04219d3b2fd0898f5e62f324503b2b94
Stats:     6 lines in 2 files changed: 5 ins; 0 del; 1 mod

8346714: [ASAN] compressedKlass.cpp reported applying non-zero offset to null pointer

Reviewed-by: mdoerr, coleenp

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PR: https://git.openjdk.org/jdk/pull/22848