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[3.14] gh-159244: Fix crash in dict() on a concurrently mutated key/value pair (GH-159245) - #160587
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… key/value pair (pythonGH-159245) In the free-threaded build, dict() and dict.update() checked that a list key/value pair had two items and then read them with borrowed references without holding its lock, so another thread could empty the list in between and the items were read from a freed or NULL array. (cherry picked from commit eaab974) Co-authored-by: Christian Aurich Zanettini Martins <christian.aurichzm@gmail.com>
This was referenced Oct 24, 2026
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In the free-threaded build, dict() and dict.update() checked that a
list key/value pair had two items and then read them with borrowed
references without holding its lock, so another thread could empty
the list in between and the items were read from a freed or NULL
array.
(cherry picked from commit eaab974)
Co-authored-by: Christian Aurich Zanettini Martins christian.aurichzm@gmail.com
The test-file conflict was resolved by adding only this regression test to 3.14 and importing
Event. The C change is unchanged from the original commit.Validation: free-threaded debug build;
test_dict,test_capi.test_dict, andtest_free_threading.test_dict(161 tests passed).