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Fix use-after-free with nested FFI::addr() calls #9599

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Fix use-after-free with nested FFI::addr() calls #9599

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11 changes: 11 additions & 0 deletions ext/ffi/ffi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,7 @@ typedef struct _zend_ffi_cdata {
zend_ffi_type *type;
void *ptr;
void *ptr_holder;
zend_object *ptr_obj;
zend_ffi_flags flags;
} zend_ffi_cdata;

Expand Down Expand Up @@ -249,6 +250,7 @@ static zend_object *zend_ffi_cdata_new(zend_class_entry *class_type) /* {{{ */

cdata->type = NULL;
cdata->ptr = NULL;
cdata->ptr_obj = NULL;
cdata->flags = 0;

return &cdata->std;
Expand Down Expand Up @@ -439,6 +441,7 @@ static zend_never_inline zend_ffi_cdata *zend_ffi_cdata_to_zval_slow(void *ptr,
cdata->type = type;
cdata->flags = flags;
cdata->ptr = ptr;
cdata->ptr_obj = NULL;
return cdata;
}
/* }}} */
Expand All @@ -453,6 +456,7 @@ static zend_never_inline zend_ffi_cdata *zend_ffi_cdata_to_zval_slow_ptr(void *p
cdata->flags = flags;
cdata->ptr = (void*)&cdata->ptr_holder;
*(void**)cdata->ptr = *(void**)ptr;
cdata->ptr_obj = NULL;
return cdata;
}
/* }}} */
Expand All @@ -478,6 +482,7 @@ static zend_never_inline zend_ffi_cdata *zend_ffi_cdata_to_zval_slow_ret(void *p
} else {
cdata->ptr = ptr;
}
cdata->ptr_obj = NULL;
return cdata;
}
/* }}} */
Expand Down Expand Up @@ -2321,6 +2326,9 @@ static void zend_ffi_cdata_dtor(zend_ffi_cdata *cdata) /* {{{ */
pefree(cdata->ptr_holder, cdata->flags & ZEND_FFI_FLAG_PERSISTENT);
}
}
if (cdata->ptr_obj) {
zend_object_release(cdata->ptr_obj);
}
}
/* }}} */

Expand Down Expand Up @@ -2426,6 +2434,7 @@ static zval *zend_ffi_read_var(zend_object *obj, zend_string *var_name, int read
cdata->flags = ZEND_FFI_FLAG_CONST;
cdata->ptr_holder = sym->addr;
cdata->ptr = &cdata->ptr_holder;
cdata->ptr_obj = NULL;
ZVAL_OBJ(rv, &cdata->std);
} else {
ZVAL_LONG(rv, sym->value);
Expand Down Expand Up @@ -4179,6 +4188,8 @@ ZEND_METHOD(FFI, addr) /* {{{ */
new_cdata->type = ZEND_FFI_TYPE_MAKE_OWNED(new_type);
new_cdata->ptr_holder = cdata->ptr;
new_cdata->ptr = &new_cdata->ptr_holder;
Z_ADDREF_P(zv);
new_cdata->ptr_obj = Z_OBJ_P(zv);

if (GC_REFCOUNT(&cdata->std) == 1 && Z_REFCOUNT_P(arg) == 1) {
if (ZEND_FFI_TYPE_IS_OWNED(cdata->type)) {
Expand Down
27 changes: 27 additions & 0 deletions ext/ffi/tests/gh9598.phpt
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@@ -0,0 +1,27 @@
--TEST--
GH-9598: Fix use-after-free for nested FFI::addr() calls
--SKIPIF--
<?php
if (!extension_loaded('ffi')) die('skip ffi extension not available');
?>
--INI--
ffi.enable=1
--FILE--
<?php

$ffi = \FFI::cdef(<<<'CPP'
typedef struct {
int8_t a;
} Example;
CPP);

$struct = $ffi->new('Example');
$structPtrPtr = \FFI::addr(\FFI::addr($struct));
var_dump($structPtrPtr[0][0]);

?>
--EXPECTF--
object(FFI\CData:struct <anonymous>)#6 (1) {
["a"]=>
int(0)
}