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When you do an assignment between two zvals (no, not zval*), you copy all fields. This includes the additional u2 data. So that means for example the Z_NEXT index gets copied, which in some cases can therefore cause a cycle in zend_hash lookups. Instead of doing an assignment, we should be doing a ZVAL_COPY (or ZVAL_COPY_VALUE for non-refcounting cases). This avoids copying u2.
ndossche
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Aug 30, 2023
When you do an assignment between two zvals (no, not zval*), you copy all fields. This includes the additional u2 data. So that means for example the Z_NEXT index gets copied, which in some cases can therefore cause a cycle in zend_hash lookups. Instead of doing an assignment, we should be doing a ZVAL_COPY (or ZVAL_COPY_VALUE for non-refcounting cases). This avoids copying u2. Closes GH-12086.
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When you do an assignment between two zvals (no, not zval*), you copy all fields. This includes the additional u2 data. So that means for example the Z_NEXT index gets copied, which in some cases can therefore cause a cycle in zend_hash lookups.
Instead of doing an assignment, we should be doing a ZVAL_COPY (or ZVAL_COPY_VALUE for non-refcounting cases). This avoids copying u2.
EDIT: as a side note, I wonder if there's more mistakes like this in spl (or other code) 🤔