Public Date:
1516514: CVE-2017-1000405 kernel: pmd can become dirty without going through a COW cycle
A flaw was found in the patches used to fix the 'dirtycow' vulnerability (CVE-2016-5195). An attacker, able to run local code, can exploit a race condition in transparent huge pages to modify usually read-only huge pages.

Find out more about CVE-2017-1000405 from the MITRE CVE dictionary dictionary and NIST NVD.


From the initial flaw description released, this issue does not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2. They do not contain the upstream commit (8310d48b125d19fcd9521d83b8293e63eb1646aa) which allows the race condition.

This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 7 for ARM and Red Hat Enterprise Linux for Power LE.

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

For further information please refer to the vulnerability article in the Customer Portal:

CVSS v3 metrics

CVSS3 Base Score 6.1
CVSS3 Base Metrics CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Impact High
Availability Impact Low

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux 7 (kernel-alt) RHSA-2018:0180 2018-01-25

Affected Packages State

Platform Package State
Red Hat Enterprise MRG 2 realtime-kernel Not affected
Red Hat Enterprise Linux 7 kernel-rt Not affected
Red Hat Enterprise Linux 7 kernel Not affected
Red Hat Enterprise Linux 6 kernel Not affected
Red Hat Enterprise Linux 5 kernel Not affected
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.


Red Hat would like to thank Eylon Ben Yaakov and Daniel Shapiro for reporting this issue.


Disabling the use of zero page:

It is possible to prevent the zero page from being mapped as a huge page, by modifying a configuration tunable in the /sys directory as shown below. This prevents the flaw from being exercised in this method.

# echo 0 > /sys/kernel/mm/transparent_hugepage/use_zero_page

Disabling huge pages:

It is possible to mitigate this flaw by disabling hugepages on a system. Some user applications may require hugepages to be performant, and may suffer a performance penalty when running without hugepages.

Red Hat has existing solutions created instructing how to disable transparent

How to disable transparent hugepages (THP) on Red Hat Enterprise Linux 7

If your application may require transparent huge pages, please consult your software vendor to confirm.

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