Fix crash in pthread_tsd_cleanup on macOS ARM64 (#1177) #1178
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Complete the NULL handling fix from commit 515047b by also checking for NULL page entries in the 2-level page map lookup. The issue occurs on macOS ARM64 during pthread TSD cleanup when thread_local C++ objects are destroyed. During this late cleanup phase, the TLS for mimalloc may already be invalidated, causing page map lookups to return NULL for valid pointers. Commit 515047b changed the sub==NULL case to return _mi_page_empty instead of NULL, but missed the case where sub[sub_idx] is NULL.
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@microsoft-github-policy-service agree company="Microsoft" |
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@austenstone I'm digging further, but this change trips the UB sanitizer on my ARM Mac when landed against the dev3 branch. I see you've landed it against the dev3-cdb branch, which I can't find documented anywhere, so that might be my problem. |
Yes, it is not recommended to use the dev3-cdb branch. I believe this issue is not present for the dev3 branch (or dev2 or dev1) (at least, I cannot reproduce it). Let me know if switching to |
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Fixes #1177
On macOS ARM64, freeing memory during thread exit can crash when
thread_localC++ objects are involved. The issue is that_mi_checked_ptr_pagechecks forsub == NULLbut not forsub[sub_idx] == NULL- commit 515047b fixed the first case but missed the second.This adds the missing NULL check so both cases return
_mi_page_emptyconsistently.