SEGV array.c

[YuanchengJiang]

Description

The following code:

<?php
set_error_handler(function ($fusion, $errstr) {
global $nan;
$nan = bin2hex(random_bytes(4));
});
settype($nan, 'object');
try {prev($nan);} catch (Exception $e) { echo($e); }

Resulted in this output:

/home/phpfuzz/WorkSpace/flowfusion/php-src/ext/standard/array.c:1009:25: runtime error: member access within misaligned address 0x3534653331653939 for type 'const zend_object_handlers' (aka 'const struct _zend_object_handlers'), which requires 8 byte alignment
0x3534653331653939: note: pointer points here
<memory cannot be printed>
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/phpfuzz/WorkSpace/flowfusion/php-src/ext/standard/array.c:1009:25 in 

To reproduce:

./php-src/sapi/cli/php  ./test.php

Commit:

3ac43296aad7942f6602840f0d42a43a4f3f5ebf

Configurations:

CC="clang-12" CXX="clang++-12" CFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" CXXFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" ./configure --enable-debug --enable-address-sanitizer --enable-undefined-sanitizer --enable-re2c-cgoto --enable-fpm --enable-litespeed --enable-phpdbg-debug --enable-zts --enable-bcmath --enable-calendar --enable-dba --enable-dl-test --enable-exif --enable-ftp --enable-gd --enable-gd-jis-conv --enable-mbstring --enable-pcntl --enable-shmop --enable-soap --enable-sockets --enable-sysvmsg --enable-zend-test --with-zlib --with-bz2 --with-curl --with-enchant --with-gettext --with-gmp --with-mhash --with-ldap --with-libedit --with-readline --with-snmp --with-sodium --with-xsl --with-zip --with-mysqli --with-pdo-mysql --with-pdo-pgsql --with-pgsql --with-sqlite3 --with-pdo-sqlite --with-webp --with-jpeg --with-freetype --enable-sigchild --with-readline --with-pcre-jit --with-iconv

Operating System:

Ubuntu 20.04 Host, Docker 0599jiangyc/flowfusion:latest

This report is automatically generated by FlowFusion

PHP Version

nightly

Operating System

No response

[ndossche]

get_ht_for_iap emits a deprecation and thereafter assumes the zval is still an object.
To solve this we'd need to fetch the properties and add protection to the hash table before emitting the deprecation; or detect clobbering. This fits in the broader issue of #20018, and given that this is caused by deprecated functionality I'm not even sure if we should attempt to fix this (urgently).

Cleaned up reproducer:

<?php
set_error_handler(function () {
    global $nan;
    $nan = 0;
});
$nan = new stdClass;
prev($nan);