Bug 1314253 - kernel: Partial SMAP bypass on 64-bit Linux kernels
Summary: kernel: Partial SMAP bypass on 64-bit Linux kernels
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1314255 1316055 1316056 1316057
Blocks: 1314257
TreeView+ depends on / blocked
 
Reported: 2016-03-03 09:52 UTC by Adam Mariš
Modified: 2021-02-17 04:14 UTC (History)
30 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2019-06-08 02:49:15 UTC
Embargoed:

Attachments (Terms of Use)

Description Adam Mariš 2016-03-03 09:52:45 UTC 
Linux kernel built with the Supervisor Mode Access Prevention(CONFIG_X86_SMAP)
and the IA32 Emulation(CONFIG_IA32_EMULATION) support is vulnerable to a partial SMAP protection bypass issue. It occurs because the 'AC' processor flag, which controls kernel mode access to user-space memory pages is not cleared when invoking IA32 system calls on 64-bit machines.

A process/user could potentially use this issue to various malicious ends.

Note: user would still need a vulnerability which can be leveraged to exploit the missing SMAP protection.

Upstream patch:
---------------
  -> https://git.kernel.org/linus/3d44d51bd339766f0178f0cf2e8d048b4a4872aa

Reference:
----------
  -> http://seclists.org/oss-sec/2016/q1/446
Comment 1 Adam Mariš 2016-03-03 09:53:41 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1314255]
Comment 2 Prasad Pandit 2016-03-09 10:21:35 UTC 
Statement:

This issue does not affect the versions of Linux kernel as shipped with
Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6.

This issue affects the version of the kernel package as shipped with Red Hat Enterprise Linux 7 and Red Hat Enterprise MRG 2.

This has been rated as having Low 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 Fedora Update System 2016-03-11 13:26:19 UTC 
kernel-4.4.4-301.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
Comment 8 Fedora Update System 2016-03-12 00:51:14 UTC 
kernel-4.4.4-200.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
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