Another UAF in DOM -> cloneNode

[chibinz]

Description

The following code:

<?php
$v0 = new DOMElement ( "jg" );
$v1 = new DOMDocument ( "Zb" );
$v2 = new DOMElement ( "IU" );
$v7 = new DOMElement ( "L" , null , "df" );
$v9 = new DOMDocument (  );

try { $v1 -> insertBefore ( $v0 , $v9 ); } catch (\Throwable) { }
$v0 -> replaceChildren ( $v7 );
$v7 -> before ( $v2 );
$v1 -> insertBefore ( $v0 );
$v2 -> cloneNode (  );

Resulted in this output:

==956555==ERROR: AddressSanitizer: heap-use-after-free on address 0x60c000008bc8 at pc 0x5600b97a4d2c bp 0x7ffe6424ba00 sp 0x7ffe6424b9f8
READ of size 4 at 0x60c000008bc8 thread T0
    #0 0x5600b97a4d2b in dom_objects_free_storage /tmp/php-asan/ext/dom/php_dom.c:1449:13
    #1 0x5600ba960c1b in zend_objects_store_del /tmp/php-asan/Zend/zend_objects_API.c:194:4
    #2 0x5600ba9c75b6 in rc_dtor_func /tmp/php-asan/Zend/zend_variables.c:57:2
    #3 0x5600ba9c76a4 in i_zval_ptr_dtor /tmp/php-asan/Zend/zend_variables.h:45:4
    #4 0x5600ba9c75f4 in zval_ptr_dtor /tmp/php-asan/Zend/zend_variables.c:84:2
    #5 0x5600ba85d919 in _zend_hash_del_el_ex /tmp/php-asan/Zend/zend_hash.c:1487:3
    #6 0x5600ba85c9ea in _zend_hash_del_el /tmp/php-asan/Zend/zend_hash.c:1514:2
    #7 0x5600ba86592a in zend_hash_reverse_apply /tmp/php-asan/Zend/zend_hash.c:2230:5
    #8 0x5600ba581ce0 in shutdown_destructors /tmp/php-asan/Zend/zend_execute_API.c:262:4
    #9 0x5600ba9e026e in zend_call_destructors /tmp/php-asan/Zend/zend.c:1330:3
    #10 0x5600ba1fee5f in php_request_shutdown /tmp/php-asan/main/main.c:1912:3
    #11 0x5600ba9ef984 in do_cli /tmp/php-asan/sapi/cli/php_cli.c:1106:3
    #12 0x5600ba9eb32c in main /tmp/php-asan/sapi/cli/php_cli.c:1310:18
    #13 0x7ff24be29d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #14 0x7ff24be29e3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #15 0x5600b9402de4 in _start (/workspaces/TriFuzz/targets/php-asan/bin/php+0x402de4)

0x60c000008bc8 is located 8 bytes inside of 120-byte region [0x60c000008bc0,0x60c000008c38)
freed by thread T0 here:
    #0 0x5600b9487702 in free /opt/llvm-15-build/llvm-15.x/final/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:52:3
    #1 0x7ff24c2c280b in xmlFreeNodeList (/lib/x86_64-linux-gnu/libxml2.so.2+0x6480b) (BuildId: aebf8e42966c3ce475ff9d9d51a762831adcbb61)

previously allocated by thread T0 here:
    #0 0x5600b94879ae in malloc /opt/llvm-15-build/llvm-15.x/final/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:69:3
    #1 0x7ff24c2c05f4 in xmlNewNode (/lib/x86_64-linux-gnu/libxml2.so.2+0x625f4) (BuildId: aebf8e42966c3ce475ff9d9d51a762831adcbb61)

SUMMARY: AddressSanitizer: heap-use-after-free /tmp/php-asan/ext/dom/php_dom.c:1449:13 in dom_objects_free_storage
Shadow bytes around the buggy address:
  0x0c187fff9120: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
  0x0c187fff9130: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c187fff9140: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
  0x0c187fff9150: fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa fa
  0x0c187fff9160: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa
=>0x0c187fff9170: fa fa fa fa fa fa fa fa fd[fd]fd fd fd fd fd fd
  0x0c187fff9180: fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa fa
  0x0c187fff9190: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa
  0x0c187fff91a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c187fff91b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c187fff91c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==956555==ABORTING

Sorry for the spam, hopefully last batch of bugs in DOMNode:)

PHP Version

PHP 8.5.0-dev

Operating System

No response

[nielsdos]

Ancient bug as well :(
Looks like it first changes some data of the node and only then checks for some pre-conditions in this case; breaking constraints...