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Bug 1479307 (CVE-2017-1000112)

Summary:	CVE-2017-1000112 kernel: Exploitable memory corruption due to UFO to non-UFO path switch
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	aquini, bhu, blc, dhoward, fhrbata, gansalmon, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jforbes, jkacur, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, madhu.chinakonda, matt, mchehab, mcressma, mlangsdo, mleitner, mmilgram, nmurray, pholasek, plougher, rt-maint, rvrbovsk, santony, security-response-team, slawomir, vdronov, williams, wmealing, yozone
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	An exploitable memory corruption flaw was found in the Linux kernel. The append path can be erroneously switched from UFO to non-UFO in ip_ufo_append_data() when building an UFO packet with MSG_MORE option. If unprivileged user namespaces are available, this flaw can be exploited to gain root privileges.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 03:20:10 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:	1480465, 1481529, 1481530, 1481531, 1481532, 1481533, 1481534, 1481535, 1481536, 1481537, 1640510, 1725185
Bug Blocks:

Description Andrej Nemec 2017-08-08 10:49:42 UTC

A memory corruption issue was found in the Linux kernel. 

When building a UFO packet with MSG_MORE __ip_append_data() calls
ip_ufo_append_data() to append. However in between two send() calls,
the append path can be switched from UFO to non-UFO one, which leads
to a memory corruption.

In case UFO packet lengths exceeds MTU, copy = maxfraglen - skb->len
becomes negative on the non-UFO path and the branch to allocate new
skb is taken. This triggers fragmentation and computation of fraggap =
skb_prev->len - maxfraglen. Fraggap can exceed MTU, causing copy =
datalen - transhdrlen - fraggap to become negative. Subsequently
skb_copy_and_csum_bits() writes out-of-bounds.

Introducing commit:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e89e9cf539a2

Comment 1 Andrej Nemec 2017-08-08 10:49:54 UTC

Acknowledgments:

Name: Andrey Konovalov

Comment 2 Adam Mariš 2017-08-11 08:08:16 UTC

Public via:

http://seclists.org/oss-sec/2017/q3/277

Comment 3 Adam Mariš 2017-08-11 08:08:59 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1480465]

Comment 5 Wade Mealing 2017-08-15 03:57:19 UTC

Statement:

This issue affects the Linux kernel packages as shipped with Red Hat
Enterprise Linux 5,6, 7 and MRG-2.

Future Linux kernel updates for the respective releases may address this issue.

Comment 7 Wade Mealing 2017-08-15 05:20:50 UTC

Additional information:

This mainly affects systems that have UFO (UDP fragment offload) enabled.

You can see if this is configured on or off with the ethool command:

# ethtool -k em1 |grep "udp-fragmentation-offload:"

udp-fragmentation-offload: off [fixed]


If enabled, disabling the UDP fragementation offload will mitigate this flaw and is documented in this solution: https://access.redhat.com/solutions/2127401

Comment 8 Marcelo Ricardo Leitner 2017-08-15 13:36:33 UTC

Fix is at: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=85f1bd9a7b5a79d5baa8bf44af19658f7bf77bfa

Comment 10 errata-xmlrpc 2017-10-19 13:27:17 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise MRG 2

Via RHSA-2017:2918 https://access.redhat.com/errata/RHSA-2017:2918

Comment 11 errata-xmlrpc 2017-10-19 15:06:56 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:2930 https://access.redhat.com/errata/RHSA-2017:2930

Comment 12 errata-xmlrpc 2017-10-19 15:10:32 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:2931 https://access.redhat.com/errata/RHSA-2017:2931

Comment 16 errata-xmlrpc 2017-11-14 20:39:08 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2017:3200 https://access.redhat.com/errata/RHSA-2017:3200

Comment 18 errata-xmlrpc 2019-07-29 16:49:23 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 5.9 Long Life

Via RHSA-2019:1932 https://access.redhat.com/errata/RHSA-2019:1932

Comment 19 errata-xmlrpc 2019-07-29 16:50:18 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 5 Extended Lifecycle Support

Via RHSA-2019:1931 https://access.redhat.com/errata/RHSA-2019:1931

Comment 20 errata-xmlrpc 2019-12-10 11:58:24 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.3 Telco Extended Update Support
  Red Hat Enterprise Linux 7.3 Advanced Update Support
  Red Hat Enterprise Linux 7.3 Update Services for SAP Solutions

Via RHSA-2019:4159 https://access.redhat.com/errata/RHSA-2019:4159