Bug 1080084 (CVE-2014-2580)

Summary: CVE-2014-2580 kernel: xen: Linux netback crash trying to disable due to malformed packet
Product: [Other] Security Response Reporter: Petr Matousek <pmatouse>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: agordeev, anton, davej, dhoward, drjones, gansalmon, imammedo, itamar, jforbes, jkurik, jonathan, jwboyer, kernel-maint, lwang, madhu.chinakonda, mchehab, mmcallis, mrezanin, pbonzini, pholasek, plougher, rkrcmar, rvrbovsk, xen-maint
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: 2014-03-24 16:27:06 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1080086    
Bug Blocks: 1080095    

Description Petr Matousek 2014-03-24 16:24:59 UTC 
When Linux's netback sees a malformed packet, it tries to disable the interface which serves the misbehaving frontend.

This involves taking a mutex, which might sleep.  But in recent versions of Linux the guest transmit path is handled by NAPI in softirq context, where sleeping is not allowed.  The end result is that the backend domain (often, Dom0) crashes with "scheduling while atomic".

Malicious guest administrators can cause denial of service.  If driver domains are not in use, the impact is a host crash.

References:
http://seclists.org/oss-sec/2014/q1/646

Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Török Edwin for discovering this bug.
Comment 1 Petr Matousek 2014-03-24 16:27:06 UTC 
Statement:

Not vulnerable.

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

This issue does not affect versions of Linux kernel packages as shipped with Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG 2 as they do not have support for Xen hypervisor.
Comment 2 Petr Matousek 2014-03-24 16:27:38 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1080086]
Comment 3 Murray McAllister 2014-03-25 04:46:25 UTC 
MITRE assigned CVE-2014-2580 to this issue:

http://seclists.org/oss-sec/2014/q1/648
Comment 5 Petr Matousek 2014-04-02 12:49:00 UTC 
Xen Security Advisory CVE-2014-2580 / XSA-90 version 2:

http://seclists.org/oss-sec/2014/q2/12

Upstream patch:

https://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=e9d8b2c2968499c1f96563e6522c56958d5a1d0d