ext/filter: encode 0xFF in FILTER_SANITIZE_ENCODED#22762
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php_filter_encode_url() initialized its 256-byte "must encode" table with memset(tmp, 1, sizeof(tmp) - 1), leaving tmp[255] uninitialized. Whether 0xFF got percent-encoded then depended on stack garbage; valgrind reports the read as a conditional jump on an uninitialised value. Initialize the whole table. Closes phpGH-22762
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php_filter_encode_url()builds a 256-byte table marking which bytes need percent-encoding, but initializes it withmemset(tmp, 1, sizeof(tmp) - 1), so tmp[255] is never written. Whether 0xFF gets encoded then depends on stack garbage.On PHP-8.4 it currently reads as unencoded, which is visible from userland:
valgrind on the unpatched build:
Present on 8.3 through master, targeting 8.4 as the lowest actively supported branch.