gc: scrub popped-frame stack residue in GC completeness tests#33
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Code reviewFound 1 issue — see the inline comments. |
The scrub memset ran from the buffer up to the frame header, past the end of the array: an out-of-bounds write that aborts under ASan with stack-buffer-overflow (verified empirically). Bound the memset by the array itself and route the allocating helpers through a padded-frame trampoline so their stale-pointer residue lands inside the span the scrub can legally zero, instead of in the last few words below the frame header that the buffer cannot reach. Addresses the review comment on PR #33. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017NJ25FGK2EUWCLz2PaUwbT
The garbage collector finds roots by conservatively scanning the machine stack. ASan's use-after-return fake stack relocates locals to heap memory the scan never sees, so the GC completeness tests fail under an ASan build even with a correct stack scrub. Bake detect_stack_use_after_return=0 into the test binary via __asan_default_options so ASan builds work out of the box; the rest of ASan's checks are unaffected. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_017NJ25FGK2EUWCLz2PaUwbT
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