php / php/php-src

zend_compile_file use of uninitialized memory on second request

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Bug Status: Needs Triage
Dominant language
C
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Description

Description

I'm using the zend_compile_file function for require a file in my extension.
Here is the code:

int requireFile(zval *result, char *path) {
    zend_file_handle file_handle;
    zend_op_array *new_op_array;
    zval dummy, output;
    int ret;

    ret = php_stream_open_for_zend_ex(path, &file_handle, USE_PATH|STREAM_OPEN_FOR_INCLUDE);

    if (ret != SUCCESS) {
        return FAILURE;
    }

    zend_string *filename = zend_string_init(path, strlen(path), 0);

    if (!file_handle.opened_path) {
        file_handle.opened_path = zend_string_copy(filename);
    }

    zend_string *opened_path = zend_string_copy(file_handle.opened_path);

    ZVAL_NULL(&dummy);
    if (zend_hash_add(&EG(included_files), opened_path, &dummy)) {
        new_op_array = zend_compile_file(&file_handle, ZEND_REQUIRE);
    } else {
        new_op_array = NULL;
    }
    zend_string_release_ex(opened_path, 0);

    if (new_op_array) {
        ZVAL_UNDEF(&output);
        zend_execute(new_op_array, &output);

        ZVAL_COPY_VALUE(result, &output);

        if (!EG(exception)) {
            zval_ptr_dtor(&output);
        }
    }

    zend_string_release(filename);

    destroy_op_array(new_op_array);
    efree(new_op_array);

    zend_destroy_file_handle(&file_handle);

    return SUCCESS;
}

Use the function:

zval exist, source;

ZVAL_NULL(&source);

char *basePath, *module, *filename;

size_t basePathLength = 0, moduleLength = 0, filenameLength = 0;

ZEND_PARSE_PARAMETERS_START(3, 3)
    Z_PARAM_STRING(basePath, basePathLength)
    Z_PARAM_STRING(module, moduleLength)
    Z_PARAM_STRING(filename, filenameLength)
ZEND_PARSE_PARAMETERS_END();

char *jsFilePath[] = {basePath, "/resource/", module, "/js/", filename, ".php"};

char jsFile[basePathLength + moduleLength + filenameLength + 18];

globalString(jsFile, jsFilePath, 6);

php_stat(jsFile, strlen(jsFile), FS_EXISTS, &exist);

if (Z_TYPE(exist) == IS_TRUE) {
    requireFile(&source, jsFile);

    zend_update_static_property(i18nCe, ZEND_STRL("source"), &source);

    zval_ptr_dtor(&source);
}

zval_ptr_dtor(&exist);

The globalString function:

void globalString(char result[], char *strs[], int size) {
    strcpy(result, strs[0]);

    for (int i = 1; i < size; i++) {
        strcat(result, strs[i]);
    }
}

However, when I try with the valgrind, it show Conditional jump or move depends on uninitialised value(s)

==35079== Memcheck, a memory error detector
==35079== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==35079== Using Valgrind-3.17.0 and LibVEX; rerun with -h for copyright info
==35079== Command: /root/php-bin/DEBUG/bin/php -S localhost:8000 test/index.php
==35079== Parent PID: 8
==35079== 
==35079== Conditional jump or move depends on uninitialised value(s)
==35079==    at 0x71B4220: persistent_compile_file (ZendAccelerator.c:2217)
==35079==    by 0x72A4E9F: requireFile (require.c:26)
==35079==    by 0x72A8CE3: zim_I18n_init (i18n.c:42)
==35079==    by 0x76651B: ZEND_DO_FCALL_SPEC_RETVAL_UNUSED_HANDLER (zend_vm_execute.h:1755)
==35079==    by 0x7E8E9F: execute_ex (zend_vm_execute.h:55172)
==35079==    by 0x7ED5A7: zend_execute (zend_vm_execute.h:59499)
==35079==    by 0x725AAB: zend_execute_scripts (zend.c:1694)
==35079==    by 0x83DF3F: php_cli_server_dispatch_router (php_cli_server.c:2168)
==35079==    by 0x83E153: php_cli_server_dispatch (php_cli_server.c:2208)
==35079==    by 0x83ED67: php_cli_server_recv_event_read_request (php_cli_server.c:2529)
==35079==    by 0x83F15B: php_cli_server_do_event_for_each_fd_callback (php_cli_server.c:2615)
==35079==    by 0x83A913: php_cli_server_poller_iter_on_active (php_cli_server.c:869)
==35079==  Uninitialised value was created by a heap allocation
==35079==    at 0x484EFC8: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-arm64-linux.so)
==35079==    by 0x6E79C7: __zend_malloc (zend_alloc.c:3056)
==35079==    by 0x6E649B: _malloc_custom (zend_alloc.c:2418)
==35079==    by 0x6E660F: _emalloc (zend_alloc.c:2537)
==35079==    by 0x753D07: zend_vm_stack_new_page (zend_execute.c:184)
==35079==    by 0x753D6B: zend_vm_stack_init (zend_execute.c:195)
==35079==    by 0x709BE7: init_executor (zend_execute_API.c:148)
==35079==    by 0x7240EF: zend_activate (zend.c:1212)
==35079==    by 0x67510B: php_request_startup (main.c:1725)
==35079==    by 0x83DDEB: php_cli_server_request_startup (php_cli_server.c:2130)
==35079==    by 0x83E0FF: php_cli_server_dispatch (php_cli_server.c:2199)
==35079==    by 0x83ED67: php_cli_server_recv_event_read_request (php_cli_server.c:2529)
==35079== 
==35079== 
==35079== HEAP SUMMARY:
==35079==     in use at exit: 5,032 bytes in 14 blocks
==35079==   total heap usage: 15,982 allocs, 15,968 frees, 3,843,232 bytes allocated
==35079== 
==35079== LEAK SUMMARY:
==35079==    definitely lost: 0 bytes in 0 blocks
==35079==    indirectly lost: 0 bytes in 0 blocks
==35079==      possibly lost: 0 bytes in 0 blocks
==35079==    still reachable: 5,032 bytes in 14 blocks
==35079==         suppressed: 0 bytes in 0 blocks
==35079== Reachable blocks (those to which a pointer was found) are not shown.
==35079== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==35079== 
==35079== For lists of detected and suppressed errors, rerun with: -s
==35079== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

PHP 8.0.21-dev (cli) (built: Sep 12 2022 14:44:12) ( NTS DEBUG )
Copyright (c) The PHP Group
Zend Engine v4.0.21-dev, Copyright (c) Zend Technologies
with Zend OPcache v8.0.21-dev, Copyright (c), by Zend Technologies

PHP Version

PHP 8.0.21-dev

Operating System

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the second-request Valgrind report with the extension code, then inspect require.c:26 and ZendAccelerator.c:2217 from the stack trace. Compare the file-handle and compiled-op-array state across requests and determine whether the uninitialized value comes from PHP or the extension usage. Done means the source of the warning is established and a focused regression test or confirmed user-code issue is documented.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, php
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
28/100

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