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ext/filter: fix use-after-free in parse_str() with filter.default - #22765
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ext/filter: fix use-after-free in parse_str() with filter.default#22765iliaal wants to merge 1 commit into
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php_sapi_filter() re-exported PARSE_STRING results through Z_STRLEN/Z_STRVAL without checking the type php_zval_filter() left behind. A validation failure frees the string and stores IS_FALSE, so the macros read the freed zend_string; a successful FILTER_VALIDATE_INT stores IS_LONG, so they dereference the integer as a pointer. Convert with zval_get_string() before writing back. ClosesphpGH-22765
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| } | ||
| if (retval) { | ||
| zend_string *str = zval_get_string(&new_var); |
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Correct. Could use the _tmp_ version to avoid refcounting, but not critical
php_sapi_filter() re-exported PARSE_STRING results through Z_STRLEN/Z_STRVAL without checking the type php_zval_filter() left behind. A validation failure frees the string and stores IS_FALSE, so the macros read the freed zend_string; a successful FILTER_VALIDATE_INT stores IS_LONG, so they dereference the integer as a pointer. Convert with zval_get_tmp_string() before writing back. ClosesphpGH-22765
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php_sapi_filter()re-exports parse_str() results throughZ_STRLEN/Z_STRVALwithout checking what typephp_zval_filter()left behind. A failed validation frees the string and stores IS_FALSE, so the macros read the freed zend_string; a successfulFILTER_VALIDATE_INTstores IS_LONG, so they dereference the integer as a pointer.Reproducer, with filter.default set:
ASAN on 8.4, unpatched:
Convert with
zval_get_string()before writing back. Present on 8.3 through master, targeting 8.4 as the lowest actively supported branch.