Note: This is a public test instance of Red Hat Bugzilla. The data contained within is a snapshot of the live data so any changes you make will not be reflected in the production Bugzilla. Email is disabled so feel free to test any aspect of the site that you want. File any problems you find or give feedback at bugzilla.redhat.com.
Bug 1479307 (CVE-2017-1000112) - CVE-2017-1000112 kernel: Exploitable memory corruption due to UFO to non-UFO path switch
Summary: CVE-2017-1000112 kernel: Exploitable memory corruption due to UFO to non-UFO ...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2017-1000112
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1480465 1481529 1481530 1481531 1481532 1481533 1481534 1481535 1481536 1481537 1640510 1725185
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-08-08 10:49 UTC by Andrej Nemec
Modified: 2021-03-11 15:32 UTC (History)
39 users (show)

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.
Clone Of:
Environment:
Last Closed: 2019-06-08 03:20:10 UTC
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2017:2918 0 normal SHIPPED_LIVE Important: kernel-rt security and bug fix update 2017-10-19 17:24:24 UTC
Red Hat Product Errata RHSA-2017:2930 0 normal SHIPPED_LIVE Important: kernel security and bug fix update 2017-10-19 18:47:35 UTC
Red Hat Product Errata RHSA-2017:2931 0 normal SHIPPED_LIVE Important: kernel-rt security and bug fix update 2017-10-19 18:48:35 UTC
Red Hat Product Errata RHSA-2017:3200 0 normal SHIPPED_LIVE Important: kernel security and bug fix update 2017-11-15 01:34:41 UTC
Red Hat Product Errata RHSA-2019:1931 0 None None None 2019-07-29 16:50:20 UTC
Red Hat Product Errata RHSA-2019:1932 0 None None None 2019-07-29 16:49:25 UTC
Red Hat Product Errata RHSA-2019:4159 0 None None None 2019-12-10 11:58:27 UTC

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
Note You need to log in before you can comment on or make changes to this bug.