CVE-2017-1000405 Detail

Current Description

The Linux Kernel versions 2.6.38 through 4.14 have a problematic use of pmd_mkdirty() in the touch_pmd() function inside the THP implementation. touch_pmd() can be reached by get_user_pages(). In such case, the pmd will become dirty. This scenario breaks the new can_follow_write_pmd()'s logic - pmd can become dirty without going through a COW cycle. This bug is not as severe as the original "Dirty cow" because an ext4 file (or any other regular file) cannot be mapped using THP. Nevertheless, it does allow us to overwrite read-only huge pages. For example, the zero huge page and sealed shmem files can be overwritten (since their mapping can be populated using THP). Note that after the first write page-fault to the zero page, it will be replaced with a new fresh (and zeroed) thp.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  7.0 HIGH
Vector:  CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H


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Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
http://www.securityfocus.com/bid/102032 Third Party Advisory  VDB Entry 
http://www.securitytracker.com/id/1040020
https://access.redhat.com/errata/RHSA-2018:0180
https://medium.com/bindecy/huge-dirty-cow-cve-2017-1000405-110eca132de0 Exploit  Issue Tracking  Third Party Advisory 
https://source.android.com/security/bulletin/pixel/2018-02-01
https://www.exploit-db.com/exploits/43199/ Exploit  Issue Tracking  Third Party Advisory  VDB Entry 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') cwe source acceptance level NIST  

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Change History

6 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2017-1000405
NVD Published Date:
11/30/2017
NVD Last Modified:
02/12/2018
Source:
MITRE