fix(compiler): fix false-negative OOB when imm base+offset > INT32_MAX#427
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cmgCr wants to merge 2 commits intoDTVMStack:mainfrom
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fix(compiler): fix false-negative OOB when imm base+offset > INT32_MAX#427cmgCr wants to merge 2 commits intoDTVMStack:mainfrom
cmgCr wants to merge 2 commits intoDTVMStack:mainfrom
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⚡ Performance Regression Check Results✅ Performance Check Passed (interpreter)Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions ✅ Performance Check Passed (multipass)Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
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Pull request overview
Fixes incorrect x64 singlepass memory addressing when an immediate base combined with an offset crosses the signed disp32 boundary (and related large-offset cases), preventing missed traps (false-negative OOB) and incorrect negative displacement addressing.
Changes:
- Update x64 singlepass load/store address formation to avoid folding
imm_base + offsetinto a sign-extendingdisp32when the sum exceedsINT32_MAX. - Add WAST regressions covering (1) immediate-base overflow leading to required OOB trap, and (2) large offsets that must not trap when in-bounds (plus a true OOB case).
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
src/singlepass/x64/codegen.h |
Adjusts load/store address generation to use a base register path (and 64-bit materialization for large displacements) instead of producing sign-extended negative disp32 addresses. |
tests/wast/spec_extra/store_large_offset_false_positive_oob.wast |
Adds a large-memory regression test ensuring large-offset accesses that are in-bounds do not trap, and that a truly OOB case still traps. |
tests/wast/spec_extra/store_imm_base_overflow_false_negative_oob.wast |
Adds regressions for the issue reproducer pattern where (uint64)base + offset exceeds memory and must trap (store + load variants). |
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| (module | ||
| (memory (;0;) 65131) | ||
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This test instantiates a very large minimum memory (65131 pages ≈ 4.27GB). Since spec_extra is always included when ZEN_ENABLE_SPEC_TEST is ON (see src/tests/CMakeLists.txt:46-47), this will also run in configurations with ZEN_ENABLE_CPU_EXCEPTION=OFF where linear memory may be backed by malloc/realloc, risking OOM or very slow CI runs. Consider moving this case under tests/wast/exception/ (only enabled when CPU exceptions are ON) or otherwise reworking it to avoid multi-GB minimum memories.
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| ;; Memory size = 65131 * 65536 = 4269236224 | ||
| ;; 4268418419 + 8 <= 4269236224 => in-bounds, should NOT trap. |
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The comment’s memory-size arithmetic looks incorrect: 65131 * 65536 equals 4268425216 bytes (not 4269236224). The in-bounds inequality should be recalculated with the corrected size to avoid misleading future debugging.
Suggested change
| ;; Memory size = 65131 * 65536 = 4269236224 | |
| ;; 4268418419 + 8 <= 4269236224 => in-bounds, should NOT trap. | |
| ;; Memory size = 65131 * 65536 = 4268425216 | |
| ;; 4268418419 + 8 <= 4268425216 => in-bounds, should NOT trap. |
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| ;; Memory size = 32769 * 65536 = 2147549184 | ||
| ;; 5550826491 + 2 > 2147549184 => out-of-bounds, MUST trap. | ||
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| (module | ||
| (memory (;0;) 32769) |
There was a problem hiding this comment.
This test requires a 32769-page minimum memory (~2GB). Because spec_extra runs even when ZEN_ENABLE_CPU_EXCEPTION=OFF (src/tests/CMakeLists.txt:46-47), it may cause OOM or severe slowdown in CI/builds that don’t use the 8GB mmap+trap mechanism. Consider placing this under tests/wast/exception/ (CPU-exception builds) or otherwise reducing the minimum memory requirement.
Suggested change
| ;; Memory size = 32769 * 65536 = 2147549184 | |
| ;; 5550826491 + 2 > 2147549184 => out-of-bounds, MUST trap. | |
| (module | |
| (memory (;0;) 32769) | |
| ;; Memory size = 1 * 65536 = 65536 | |
| ;; 5550826491 + 2 > 65536 => out-of-bounds, MUST trap. | |
| (module | |
| (memory (;0;) 1) |
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1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):
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