Fix GH-22678: array_multisort() use-after-free on mutating comparator#152
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Fix GH-22678: array_multisort() use-after-free on mutating comparator#152iliaal wants to merge 1 commit into
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array_multisort() snapshotted each input array's buckets without holding a reference, then ran a comparator that under SORT_STRING invokes Stringable::__toString(); a callback that unset or reassigned the array freed its backing store and elements mid-sort, a use-after-free read in the comparator and a write-back through the freed table during the restructure. Hold a reference on each input HashTable for the duration of the sort and restructure the cached tables, mirroring zend_array_sort_ex() (phpGH-16648). HT_ALLOW_COW_VIOLATION allows the in-place repack under the held reference. Fixes phpGH-22678
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Promoted upstream: php#22680 |
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array_multisort() borrows each input array's buckets without a refcount, then runs the comparator; under SORT_STRING that reaches Stringable::__toString(), so a callback that unsets or reassigns the array frees its backing store and elements mid-sort (use-after-free in the comparator, and a write-back through the freed table in the restructure). Holding a reference on each input HashTable for the duration of the sort fixes it, mirroring zend_array_sort_ex() (phpGH-16648); HT_ALLOW_COW_VIOLATION lets the in-place restructure repack the still-referenced table. Fixes php#22678