Fix GH-21731: Random\Engine\Xoshiro256StarStar::__unserialize() accepts all-zero state#21732
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TimWolla merged 1 commit intophp:PHP-8.4from Apr 12, 2026
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ext/random/tests/02_engine/xoshiro256starstar_unserialize_zero_state.phpt
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It appears you accidentally dropped the NEWS change during the rebase. Given this is a behavioral change / proper bugfix, it should be there. Do you want to add it back in, or shall I?
…cepts all-zero state The constructor rejects a seed that would leave the internal state all zero, because xoshiro256** with zero state produces 0 on every call forever. The unserialize callback didn't check the same invariant. A caller feeding a crafted serialized payload through __unserialize() ended up with a live engine that returned 0 from every operation. Match the constructor: reject the all-zero state from the unserialize callback too. The Mt19937-aliased __unserialize() wrapper turns the false return into the standard "Invalid serialization data" exception. Closes phpGH-21731
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Added it back, I went a little heavy on removals 😓 |
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Fixes #21731.
Random\Engine\Xoshiro256StarStar::__construct()rejects a seed that would leave the internal state all zero, because xoshiro256** with zero state returns0on every call forever. Theunserializecallback didn't check the same invariant. A caller feeding a crafted serialized payload through__unserialize()ended up with a live engine that returned 0 from every operation.Match the constructor: reject the all-zero state from
unserializetoo. The Mt19937-aliased__unserialize()wrapper maps thefalsereturn into the standard "Invalid serialization data for ... object" exception, so the wrapper needs no changes.