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Support neighbouring extension in the ZendMM custom handlers hook in zend_test #12792

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7 changes: 5 additions & 2 deletions ext/zend_test/php_test.h
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -56,8 +56,11 @@ ZEND_BEGIN_MODULE_GLOBALS(zend_test)
bool print_stderr_mshutdown;
zend_long limit_copy_file_range;
int observe_opline_in_zendmm;
zend_mm_heap* zend_orig_heap;
zend_mm_heap* zend_test_heap;
// previous handlers that might have been installed
// `USE_ZEND_ALLOC=0` installs custom handlers
void* (*zendmm_orig_malloc)(size_t);
void (*zendmm_orig_free)(void*);
void* (*zendmm_orig_realloc)(void *, size_t);
zend_test_fiber *active_fiber;
zend_long quantity_value;
zend_string *str_test;
Expand Down
115 changes: 90 additions & 25 deletions ext/zend_test/test.c
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -517,28 +517,110 @@ static bool has_opline(zend_execute_data *execute_data)
;
}

// When a custom memory manager is installed, ZendMM alters its behaviour. For
// example `zend_mm_gc()` will not do anything anymore, or `zend_mm_shutdown()`
// won't cleanup chunks and leak memory. This might not be a problem in tests,
// but I fear folks might see and use this implementation as a boiler plate when
// trying to use this hook
int zend_test_prepare_zendmm_for_call(zend_mm_heap *heap)
{
int flag = 0;
memcpy(&flag, heap, sizeof(int));
int new_flag = 0;
memcpy(heap, &new_flag, sizeof(int));
Comment on lines +527 to +530
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Yeah, no.
It works, but we should not do it this way, especially not advertise that in php-src itself.

You probably should include a

#ifndef ZEND_ALLOC_HIDE_STRUCTS
struct _zend_mm_heap {
#if ZEND_MM_CUSTOM
 int use_custom_mm_heap;
#endif
}
#endif

to zend_alloc.h, with #define ZEND_ALLOC_HIDE_STRUCTS 1 in zend_alloc.c

and have it public API.

If we rely on such implementation details, it can well just be public.

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@realFlowControl realFlowControl Feb 19, 2024

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Hmm, I get the point and the zend_test_prepare_zendmm_for_call() is super ugly 😉
OTOH I would rather not make the use_custom_mm_heap flag public just for the sake of this test.

I am about to prepare a PR that would add a gc and shutdown custom handler (#13432) that might help solve this.

return flag;
}

void zend_test_restore_zendmm_after_call(zend_mm_heap *heap, int flag)
{
memcpy(heap, &flag, sizeof(int));
}

void * zend_test_custom_malloc(size_t len)
{
if (has_opline(EG(current_execute_data))) {
assert(EG(current_execute_data)->opline->lineno != (uint32_t)-1);
}
return _zend_mm_alloc(ZT_G(zend_orig_heap), len ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
if (ZT_G(zendmm_orig_malloc)) {
return ZT_G(zendmm_orig_malloc)(len);
}
int flag = zend_test_prepare_zendmm_for_call(zend_mm_get_heap());
void * ptr = _zend_mm_alloc(zend_mm_get_heap(), len ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
zend_test_restore_zendmm_after_call(zend_mm_get_heap(), flag);
return ptr;
}

void zend_test_custom_free(void *ptr)
{
if (has_opline(EG(current_execute_data))) {
assert(EG(current_execute_data)->opline->lineno != (uint32_t)-1);
}
_zend_mm_free(ZT_G(zend_orig_heap), ptr ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
if (ZT_G(zendmm_orig_free)) {
ZT_G(zendmm_orig_free)(ptr);
return;
}
int flag = zend_test_prepare_zendmm_for_call(zend_mm_get_heap());
_zend_mm_free(zend_mm_get_heap(), ptr ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
zend_test_restore_zendmm_after_call(zend_mm_get_heap(), flag);
}

void * zend_test_custom_realloc(void * ptr, size_t len)
{
if (has_opline(EG(current_execute_data))) {
assert(EG(current_execute_data)->opline->lineno != (uint32_t)-1);
}
return _zend_mm_realloc(ZT_G(zend_orig_heap), ptr, len ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
if (ZT_G(zendmm_orig_realloc)) {
return ZT_G(zendmm_orig_realloc)(ptr, len);
}
int flag = zend_test_prepare_zendmm_for_call(zend_mm_get_heap());
void * new_ptr = _zend_mm_realloc(zend_mm_get_heap(), ptr, len ZEND_FILE_LINE_EMPTY_CC ZEND_FILE_LINE_EMPTY_CC);
zend_test_restore_zendmm_after_call(zend_mm_get_heap(), flag);
return new_ptr;
}

void zend_test_install_custom_mm_handler(void)
{
// fetch maybe installed previous handlers
if (!is_zend_mm()) {
zend_mm_get_custom_handlers(
zend_mm_get_heap(),
&ZT_G(zendmm_orig_malloc),
&ZT_G(zendmm_orig_free),
&ZT_G(zendmm_orig_realloc)
);
}
zend_mm_set_custom_handlers(
zend_mm_get_heap(),
zend_test_custom_malloc,
zend_test_custom_free,
zend_test_custom_realloc
);
}

void zend_test_uninstall_custom_mm_handler(void)
{
void* (*custom_malloc)(size_t);
void (*custom_free)(void*);
void* (*custom_realloc)(void *, size_t);
zend_mm_get_custom_handlers(
zend_mm_get_heap(),
&custom_malloc,
&custom_free,
&custom_realloc
);
if (custom_malloc == zend_test_custom_malloc ||
custom_free == zend_test_custom_free ||
custom_realloc == zend_test_custom_realloc) {
zend_mm_set_custom_handlers(
zend_mm_get_heap(),
ZT_G(zendmm_orig_malloc),
ZT_G(zendmm_orig_free),
ZT_G(zendmm_orig_realloc)
);
ZT_G(zendmm_orig_malloc) = NULL;
ZT_G(zendmm_orig_free) = NULL;
ZT_G(zendmm_orig_realloc) = NULL;
}
}

static PHP_INI_MH(OnUpdateZendTestObserveOplineInZendMM)
Expand All @@ -550,22 +632,9 @@ static PHP_INI_MH(OnUpdateZendTestObserveOplineInZendMM)
int int_value = zend_ini_parse_bool(new_value);

if (int_value == 1) {
// `zend_mm_heap` is a private struct, so we have not way to find the
// actual size, but 4096 bytes should be enough
ZT_G(zend_test_heap) = malloc(4096);
memset(ZT_G(zend_test_heap), 0, 4096);
zend_mm_set_custom_handlers(
ZT_G(zend_test_heap),
zend_test_custom_malloc,
zend_test_custom_free,
zend_test_custom_realloc
);
ZT_G(zend_orig_heap) = zend_mm_get_heap();
zend_mm_set_heap(ZT_G(zend_test_heap));
} else if (ZT_G(zend_test_heap)) {
free(ZT_G(zend_test_heap));
ZT_G(zend_test_heap) = NULL;
zend_mm_set_heap(ZT_G(zend_orig_heap));
zend_test_install_custom_mm_handler();
} else {
zend_test_uninstall_custom_mm_handler();
}
return OnUpdateBool(entry, new_value, mh_arg1, mh_arg2, mh_arg3, stage);
}
Expand Down Expand Up @@ -948,6 +1017,8 @@ PHP_MSHUTDOWN_FUNCTION(zend_test)

zend_test_observer_shutdown(SHUTDOWN_FUNC_ARGS_PASSTHRU);

zend_test_uninstall_custom_mm_handler();

if (ZT_G(print_stderr_mshutdown)) {
fprintf(stderr, "[zend-test] MSHUTDOWN\n");
}
Expand All @@ -970,12 +1041,6 @@ PHP_RSHUTDOWN_FUNCTION(zend_test)
} ZEND_HASH_FOREACH_END();
zend_hash_destroy(&ZT_G(global_weakmap));

if (ZT_G(zend_test_heap)) {
free(ZT_G(zend_test_heap));
ZT_G(zend_test_heap) = NULL;
zend_mm_set_heap(ZT_G(zend_orig_heap));
}

return SUCCESS;
}

Expand Down
2 changes: 0 additions & 2 deletions ext/zend_test/tests/opline_dangling.phpt
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,6 @@ possible segfault in `ZEND_BIND_STATIC`
https://github.com/php/php-src/pull/12758
--EXTENSIONS--
zend_test
--ENV--
USE_ZEND_ALLOC=1
--INI--
zend_test.observe_opline_in_zendmm=1
--FILE--
Expand Down
2 changes: 0 additions & 2 deletions ext/zend_test/tests/opline_dangling_02.phpt
View file Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,6 @@
possible segfault in `ZEND_FUNC_GET_ARGS`
--EXTENSIONS--
zend_test
--ENV--
USE_ZEND_ALLOC=1
--INI--
zend_test.observe_opline_in_zendmm=1
--FILE--
Expand Down

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