Fix: accept interior copy_to/copy_from ranges within a live allocation

[ChaoZheng109]

Problem

Issue #1537: the child-pointer provenance guard keyed every allocation by its exact (worker_id, base) and admitted a copy only when the address hit that base. A partial update of a persistent device buffer — copy_to(base + offset) into one page of a resident cache (e.g. the DeepSeek V4 decode KV cache) — was rejected as though the interior address were unknown, because the guard stored no allocation extent to range-check against.

base = orch.malloc(worker_id=0, size=64)
orch.copy_to(worker_id=0, dst=base + 32, src=host_ptr, size=16)
# before: ValueError: device pointer ... is not a live allocation

Fix

Record each allocation's byte extent in provenance and validate copies by containment instead of exact base:

base <= ptr && ptr + nbytes <= base + extent

• _ChildProvEntry now carries malloc_size and maps each CommDomain allocation id to the extent of the window / buffer recorded at that base; live_extent() returns the widest live role.
• copy_to / copy_from (Worker L2 path and Orchestrator L3 path) call the new _child_prov_require_live_range, which scans the worker's live allocations and admits any range wholly contained in one. Python ints are unbounded, so the ptr + nbytes bound is exact (no wraparound).
• CommDomain windows / carved buffers carry their live extent so interior copies into them are validated too.

free() and kind4 dispatch are unchanged — they still require the exact base, since they act on the whole allocation, not an interior slice.

Behavior

Operation	Before	After
copy_to(base + 32, ..., 16) within a malloc(64)	rejected	accepted
copy_to(base + 63, ..., 2) (overruns)	accepted (guard blind to size)	rejected — out of range
same address on another worker	rejected	rejected
copy after free(base)	rejected	rejected
free(base + 32)	rejected	rejected

Tests

Device-free, mocked-orchestrator regression coverage in tests/ut/py/test_worker/test_child_addr_guard.py for all five cases in the issue, at both the L3 orchestrator and L2 worker entry points. tests/ut/py/test_worker/ — 349 passed, 2 skipped (pre-existing).

close #1537

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📝 Walkthrough

Walkthrough

copy_to and copy_from now validate byte ranges within live allocations. Provenance tracks malloc and CommDomain extents, while free and dispatch retain exact-base requirements. Documentation and tests cover interior ranges, boundaries, aliases, worker isolation, L2 paths, and release ordering.

Changes

Child-memory provenance guards

Layer / File(s)	Summary
Extent-aware provenance model python/simpler/worker.py	Provenance entries now store malloc sizes and per-domain extents, calculate live ranges, and remove released domain extents.
Copy-path integration and API contract python/simpler/orchestrator.py, python/simpler/worker.py, docs/user/reference/python-api.md	Malloc records allocation sizes, copy operations validate requested ranges, and API documentation describes valid interior addresses and partial updates.
Provenance and memory-operation regression coverage tests/ut/py/test_worker/test_child_addr_guard.py	Tests cover contained ranges, boundary and stale-pointer rejection, exact-base free and dispatch behavior, aliases, worker isolation, L2 paths, and release ordering.

Estimated code review effort: 4 (Complex) | ~35 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant Orchestrator
  participant ChildProvenance
  participant DeviceMemory
  Caller->>Orchestrator: copy_to or copy_from with pointer and size
  Orchestrator->>ChildProvenance: Validate contained live range
  ChildProvenance-->>Orchestrator: Validation result
  Orchestrator->>DeviceMemory: Execute validated copy

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Possibly related PRs

• hw-native-sys/simpler#1430: Updates the same child-memory provenance and guard machinery.
• hw-native-sys/simpler#1538: Overlaps on recording allocation extents and enforcing contained copy ranges.

Poem

A bunny found a buffer wide,
And hopped to bytes tucked deep inside.
“Copy this range!” the guards now say,
“But free the base, the proper way.”
Extents bloom—hip-hop hooray!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly states the main behavior change: interior copy_to/copy_from ranges are now accepted within live allocations.
Description check	✅ Passed	The description matches the change and issue: it explains the range-based provenance fix and the expected copy/free behavior.
Linked Issues check	✅ Passed	The changes satisfy #1537 by adding extent-aware range validation, keeping exact-base free checks, and covering the five requested cases.
Out of Scope Changes check	✅ Passed	No clear out-of-scope changes; the docs, runtime code, and tests all support the interior-range provenance fix.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[ChaoZheng109]

/gemini review

[ChaoZheng109]

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