Fix use-after-free in Collator::sort() with a mutating comparator#22467
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iliaal wants to merge 1 commit into
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Fix use-after-free in Collator::sort() with a mutating comparator#22467iliaal wants to merge 1 commit into
iliaal wants to merge 1 commit into
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LamentXU123
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Looks Good. I think would be better to add a comment here to make sure people know why we are doing this.
devnexen
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nit: now that the manual zend_array_dup provides the isolation, the / in "Oa/|l" is a redundant eager copy when the array is shared by value (usort skips it for the same reason). Micro optimisation but might be worth it wdyt ?
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You're right once the dup runs first. Reordered so the conversion operates on the copy and the original array is never mutated, which lets the / drop like usort does. The two conversion-failure paths free the copy.
collator_sort() and collator_asort() sort the array in place while the comparator may run a __toString() that appends to the same array through a reference, reallocating its storage under the running sort. Sort a copy and swap it back, matching usort().
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devnexen
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Collator::sort() and Collator::asort() with COLLATOR_SORT_REGULAR use each object element's __toString() as the comparison key. If that __toString() appends to the array being sorted (reachable through a reference), the array's backing storage is reallocated while zend_hash_sort() still holds pointers into it, a use-after-free. usort() already avoids this by duplicating the array before sorting; Collator now does the same.