Bug 1226290 (CVE-2015-4163, xsa134)

Summary: CVE-2015-4163 xen: GNTTABOP_swap_grant_ref operation misbehavior (xsa-134)
Product: [Other] Security Response Reporter: Martin Prpič <mprpic>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: ailan, drjones, imammedo, knoel, mrezanin, pbonzini, pmatouse, rkrcmar, security-response-team, vkuznets
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
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Clone Of: Environment:
Last Closed: 2015-05-29 12:15:32 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1226292    
Attachments:
Description Flags
xsa134.patch none

Description Martin Prpič 2015-05-29 11:33:30 UTC 
ISSUE DESCRIPTION
=================

With the introduction of version 2 grant table operations, a version check became necessary for most grant table related hypercalls. The GNTTABOP_swap_grant_ref call was lacking such a check. As a result, the subsequent code behaved as if version 2 was in use, when a guest issued this hypercall without a prior GNTTABOP_setup_table or GNTTABOP_set_version.

The effect is a possible NULL pointer dereferences. However, this cannot be exploited to elevate privileges of the attacking domain, as the maximum memory address that can be wrongly accessed this way is bounded to far below the start of hypervisor memory.

IMPACT
======

Malicious or buggy guest domain kernels can mount a denial of service attack which, if successful, can affect the whole system.


Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue.
Comment 1 Martin Prpič 2015-05-29 12:09:32 UTC 
Created attachment 1032041 [details]
xsa134.patch
Comment 3 Petr Matousek 2015-05-29 12:15:32 UTC 
Statement:

Not vulnerable.

This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.