[SYCL][Unittests] Don't pass addresses of local variables as UR handles in unit tests

[uditagarwal97]

Problem

The UR mock adapter reinterpret_casts every handle it receives to mock::dummy_handle_t_ and touches MRefCounter on retain/release. Three unit tests passed the address of a local variable where the runtime expects a handle, so those retain/release calls wrote into the tests' own stack frames.

1. sycl/unittests/Extensions/BindlessImages/Semaphores.cpp — BindlessImagesExtensionTests.ExternalSemaphoreSignal built fake device events with

int DummyInt1 = 0, DummyInt2 = 0;
DummyEventImpl1->setHandle(reinterpret_cast<ur_event_handle_t>(&DummyInt1));
DummyEventImpl2->setHandle(reinterpret_cast<ur_event_handle_t>(&DummyInt2));

~event_impl() calls urEventRelease on those handles:

ERROR: AddressSanitizer: stack-buffer-overflow on address ...
WRITE of size 8 at ... thread T0
    #0 ... in operator-- bits/atomic_base.h:410
    #1 ... in releaseDummyHandle<ur_event_handle_t_ *>
       unified-runtime/source/mock/ur_mock_helpers.hpp:74
    #2 ... in driver::urEventRelease(ur_event_handle_t_*)
    ...
    #6 ... in sycl::_V1::detail::event_impl::~event_impl()
    #10 ... in BindlessImagesExtensionTests_ExternalSemaphoreSignal_Test::TestBody()

The same pattern also produced a UBSan member access within misaligned address ... for type 'dummy_handle_t_' diagnostic, because a 4-byte-aligned int is not suitably aligned for the handle struct.

2. sycl/unittests/thread_safety/InteropKernelEnqueue.cpp (KernelEnqueue.InteropKernel) and 3. sycl/unittests/handler/SetArgForLocalAccessor.cpp (HandlerSetArg.LocalAccessor) — both created a native handle and then passed its address to make_kernel:

auto Handle = mock::createDummyHandle<ur_native_handle_t>();
... reinterpret_cast<cl_kernel>(&Handle) ...

so the runtime's retain/release of the interop kernel mutated the local Handle variable, and the handle it actually created was never released (a leak on top of the corruption).

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Co-Authored-By: Claude Opus 5 (1M context) noreply@anthropic.com

[Copilot]

🟢 Approval recommended

The changes correctly eliminate invalid stack-backed handles and balance mock handle ownership.

Pull request overview

Fixes unsafe mock-handle ownership in three SYCL unit tests.

Changes:

• Replaces stack addresses with valid reference-counted dummy handles.
• Ensures interop kernels are destroyed before releasing test-owned handles.

File summaries

File	Description
sycl/unittests/thread_safety/InteropKernelEnqueue.cpp	Corrects interop kernel handle lifetime.
sycl/unittests/handler/SetArgForLocalAccessor.cpp	Corrects interop kernel handle lifetime.
sycl/unittests/Extensions/BindlessImages/Semaphores.cpp	Uses releasable dummy event handles.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Balanced

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