Fix GH-21730: Mt19937::__debugInfo() leaks state HashTable when the serialize callback fails#21733
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TimWolla merged 1 commit intophp:PHP-8.4from Apr 12, 2026
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TimWolla
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…e serialize callback fails Mt19937::__debugInfo() allocates a temporary HashTable with array_init(&t), calls the engine's serialize callback, and then inserts t into the return value. If the callback returns false, the method throws and hits RETURN_THROWS() before inserting t, so the HashTable leaks. PcgOneseq128XslRr64 and Xoshiro256StarStar alias the same method and share the leak. Niels Dossche fixed the same pattern in __serialize() via phpGH-20383 (720e006). That cleanup didn't touch __debugInfo(). Apply the same reordering here: insert t into return_value first, then let the callback populate it. RETURN_THROWS() then unwinds the return value cleanly. The path is latent in stock PHP because the three built-in serialize callbacks (mt19937, pcg, xoshiro) all return true, so no user code reaches the leak today. I'm fixing it for symmetry with phpGH-20383 and to keep the pattern from regressing if a future engine grows a failing serialize path. Closes phpGH-21730
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Fixes #21730.
Mt19937::__debugInfo()allocates a temporary HashTable witharray_init(&t)and then calls the engine'sserializecallback. If the callback returns false, the method throws "Engine serialize failed" and hitsRETURN_THROWS()before insertingt, so the HashTable leaks.PcgOneseq128XslRr64andXoshiro256StarStaralias the same method and share the leak.Niels Dossche fixed the same pattern in
__serialize()via #20383 (720e006). That cleanup didn't touch__debugInfo(). The fix here is identical: inserttinto the return value before calling the callback, soRETURN_THROWS()unwinds it cleanly on failure.The leak path is latent in stock PHP because the three built-in
serializecallbacks all returntrue, so no user code reaches it today. Fixing for symmetry with #20383 and to keep the pattern from regressing if a future engine grows a failing serialize path. Verified under valgrind with a forced-failure patch: zero definitely-lost bytes.