Bug 1297720 – php: Use-after-free in WDDX Packet Deserialization

Bug 1297720 - php: Use-after-free in WDDX Packet Deserialization

Summary:	php: Use-after-free in WDDX Packet Deserialization

Status:	CLOSED WONTFIX

Aliases:	None

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=moderate,public=20151007,repor...
Keywords:	Security

Depends On:	1297722
Blocks:	1297732
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Reported:	2016-01-12 05:17 EST by Adam Mariš
Modified:	2016-03-15 07:31 EDT (History)
CC List:	15 users (show)

See Also:
Fixed In Version:	php 5.5.31, php 5.6.17
Doc Type:	Bug Fix
Doc Text:	A use-after-free flaw was found in the php_wddx_pop_element() function of PHP's WDDX extension. Unserializing specially crafted input could cause a PHP application to crash or, possibly, execute arbitrary code.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2016-02-03 08:02:52 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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Description Adam Mariš 2016-01-12 05:17:14 EST

A use-after free vulnerability was found that could possible lead to arbitrary remote codeexecution. Vulnerable code:

if (Z_TYPE_P(ent2->data) == IS_ARRAY || Z_TYPE_P(ent2->data) == IS_OBJECT) {
	target_hash = HASH_OF(ent2->data);
	if (ent1->varname) {
		if (!strcmp(ent1->varname, PHP_CLASS_NAME_VAR) &&
			Z_TYPE_P(ent1->data) == IS_STRING && Z_STRLEN_P(ent1->data)) {
			...
			/* Clean up old array entry */
			zval_ptr_dtor(&ent2->data);
				
			/* Set stack entry to point to the newly created object */
			ent2->data = obj;
					
			/* Clean up class name var entry */
			zval_ptr_dtor(&ent1->data);

During wddx packet deserialization the zval_ptr_dtor() lead ZVAL is freed from the memory, however a crafted recordset can still use already freed memory.

Upstream patch:

https://git.php.net/?p=php-src.git;a=commit;h=366f9505a4aae98ef2f4ca39a838f628a324b746

Upstream bug (contains reproducer):

https://bugs.php.net/bug.php?id=70661

Comment 1 Adam Mariš 2016-01-12 05:18:09 EST

Created php tracking bugs for this issue:

Affects: fedora-all [bug 1297722]

Comment 2 Fedora Update System 2016-01-16 08:22:24 EST

php-5.6.17-1.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 3 Fedora Update System 2016-01-16 09:20:19 EST

php-5.6.17-1.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.

Comment 4 Cedric Buissart 2016-01-29 05:36:30 EST

Lowering the impact down to moderate based on the following :
 * WDDX packet deserialization should not be used with untrusted source :
http://php.net/manual/en/function.wddx-deserialize.php#refsect1-function.wddx-deserialize-returnvalues

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