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Bug 1243852 - (CVE-2015-5156) CVE-2015-5156 kernel: buffer overflow with fraglist larger than MAX_SKB_FRAGS + 2 in virtio-net
CVE-2015-5156 kernel: buffer overflow with fraglist larger than MAX_SKB_FRAGS...
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
: ---
: ---
Assigned To: Red Hat Product Security
impact=moderate,public=20150806,repor...
: Security
Depends On: 1245995 1245996 1247839 1247840 1247841 1247844 1266515
Blocks: 1243854
  Show dependency tree / graph
 
Reported: 2015-07-16 09:14 EDT by Vasyl Kaigorodov
Modified: 2016-05-11 03:28 EDT (History)
27 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
A buffer overflow flaw was found in the way the Linux kernel's virtio-net subsystem handled certain fraglists when the GRO (Generic Receive Offload) functionality was enabled in a bridged network configuration. An attacker on the local network could potentially use this flaw to crash the system, or, although unlikely, elevate their privileges on the system.
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Clone Of:
Environment:
Last Closed: 2016-05-11 03:28:29 EDT
Type: ---
Regression: ---
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Documentation: ---
CRM:
Verified Versions:
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2015:1977 normal SHIPPED_LIVE Moderate: kernel-rt security, bug fix, and enhancement update 2015-11-03 16:42:40 EST
Red Hat Product Errata RHSA-2015:1978 normal SHIPPED_LIVE Moderate: kernel security, bug fix, and enhancement update 2015-11-03 18:47:34 EST
Red Hat Product Errata RHSA-2016:0855 normal SHIPPED_LIVE Moderate: kernel security, bug fix, and enhancement update 2016-05-10 18:43:57 EDT

  None (edit)
Description Vasyl Kaigorodov 2015-07-16 09:14:25 EDT 
When a guests KVM network devices is in a bridge configuration the kernel can create a situation in which packets are fragmented in an unexpected fashion. The GRO functionality can create a situation in which multiple SKB's are chained together
in a single packets fraglist (by design).  

The virtio module declares support for NETIF_F_FRAGLIST and assumes that there are at most MAX_SKB_FRAGS + 2 fragments which isn't always true with a fraglist, when GRO is enabled on the incoming driver it can create more fragments than expected.

A longer than expected fragment list in the socket buffer will make the call to skb_to_sgvec overflow the sg array, leading to memory corruption.  It is unlikely that an attacker can use this as controlled memory corruption to execute arbitrary code.

Upstream patch: 
http://marc.info/?l=linux-netdev&m=143868216724068&w=2

References:
http://www.openwall.com/lists/oss-security/2015/08/06/1

Acknowledgements:

This issue was discovered by Jason Wang of Red Hat.
Comment 4 Wade Mealing 2015-07-29 00:27:30 EDT 
Statement:

This issue did not affect the Linux kernel packages as shipped with Red Hat Enterprise MRG 2.

This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5. Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Comment 7 Petr Matousek 2015-09-25 09:19:15 EDT 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1266515]
Comment 8 Fedora Update System 2015-10-16 02:57:29 EDT 
kernel-4.2.3-200.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
Comment 9 errata-xmlrpc 2015-11-03 11:43:19 EST 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2015:1977 https://rhn.redhat.com/errata/RHSA-2015-1977.html
Comment 11 Fedora Update System 2015-11-12 21:50:48 EST 
kernel-4.1.12-101.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.
Comment 12 errata-xmlrpc 2016-05-10 18:52:09 EDT 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2016:0855 https://rhn.redhat.com/errata/RHSA-2016-0855.html
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