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Fix use-after-free in extract() EXTR_REFS collision modes #155

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Fix use-after-free in extract() EXTR_REFS collision modes #155

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20 changes: 15 additions & 5 deletions ext/standard/array.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1764,8 +1764,10 @@ static zend_long php_extract_ref_if_exists(const zend_array *arr, const zend_arr
} else {
ZVAL_MAKE_REF_EX(entry, 2);
}
zval_ptr_dtor(orig_var);
zval garbage;
ZVAL_COPY_VALUE(&garbage, orig_var);
ZVAL_REF(orig_var, Z_REF_P(entry));
zval_ptr_dtor(&garbage);
count++;
}
} ZEND_HASH_FOREACH_END();
Expand Down Expand Up @@ -1957,8 +1959,10 @@ static zend_long php_extract_ref_prefix_if_exists(const zend_array *arr, zend_ar
if (Z_TYPE_P(orig_var) == IS_INDIRECT) {
orig_var = Z_INDIRECT_P(orig_var);
}
zval_ptr_dtor(orig_var);
zval garbage;
ZVAL_COPY_VALUE(&garbage, orig_var);
ZVAL_REF(orig_var, Z_REF_P(entry));
zval_ptr_dtor(&garbage);
} else {
zend_hash_add_new(symbol_table, final_name, entry);
}
Expand Down Expand Up @@ -2070,8 +2074,10 @@ prefix:;
if (Z_TYPE_P(orig_var) == IS_INDIRECT) {
orig_var = Z_INDIRECT_P(orig_var);
}
zval_ptr_dtor(orig_var);
zval garbage;
ZVAL_COPY_VALUE(&garbage, orig_var);
ZVAL_REF(orig_var, Z_REF_P(entry));
zval_ptr_dtor(&garbage);
} else {
zend_hash_add_new(symbol_table, final_name, entry);
}
Expand Down Expand Up @@ -2198,8 +2204,10 @@ static zend_long php_extract_ref_prefix_all(const zend_array *arr, zend_array *s
if (Z_TYPE_P(orig_var) == IS_INDIRECT) {
orig_var = Z_INDIRECT_P(orig_var);
}
zval_ptr_dtor(orig_var);
zval garbage;
ZVAL_COPY_VALUE(&garbage, orig_var);
ZVAL_REF(orig_var, Z_REF_P(entry));
zval_ptr_dtor(&garbage);
} else {
zend_hash_add_new(symbol_table, final_name, entry);
}
Expand Down Expand Up @@ -2300,8 +2308,10 @@ static zend_long php_extract_ref_prefix_invalid(const zend_array *arr, zend_arra
if (Z_TYPE_P(orig_var) == IS_INDIRECT) {
orig_var = Z_INDIRECT_P(orig_var);
}
zval_ptr_dtor(orig_var);
zval garbage;
ZVAL_COPY_VALUE(&garbage, orig_var);
ZVAL_REF(orig_var, Z_REF_P(entry));
zval_ptr_dtor(&garbage);
} else {
zend_hash_add_new(symbol_table, final_name, entry);
}
Expand Down
32 changes: 32 additions & 0 deletions ext/standard/tests/array/extract_refs_reentrant_dtor.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
--TEST--
extract() EXTR_REFS: destructor freeing the target symbol during the ref write (GH-18209 siblings)
--FILE--
<?php
// EXTR_IF_EXISTS path: php_extract_ref_if_exists
class A {
public function __destruct() {
unset($GLOBALS['b']);
}
}
$b = new A();
$r1 = 'r1';
extract(['b' => &$r1], EXTR_REFS | EXTR_IF_EXISTS);
var_dump($b ?? 'b-unset');

// EXTR_PREFIX_ALL path: php_extract_ref_prefix_all
class B {
public function __destruct() {
unset($GLOBALS['p_c']);
}
}
$p_c = new B();
$r2 = 'r2';
extract(['c' => &$r2], EXTR_REFS | EXTR_PREFIX_ALL, 'p');
var_dump($p_c ?? 'p_c-unset');

echo "done\n";
?>
--EXPECT--
string(7) "b-unset"
string(9) "p_c-unset"
done
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