CVE-2017-1000405

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.

• CWE-362

• http://www.securityfocus.com/bid/102032Third Party Advisory, VDB Entry
• http://www.securitytracker.com/id/1040020Third Party Advisory, VDB Entry
• https://access.redhat.com/errata/RHSA-2018:0180Third Party Advisory
• https://medium.com/bindecy/huge-dirty-cow-cve-2017-1000405-110eca132de0Exploit, Issue Tracking, Third Party Advisory
• https://source.android.com/security/bulletin/pixel/2018-02-01Third Party Advisory
• https://www.exploit-db.com/exploits/43199/Exploit, Issue Tracking, Third Party Advisory, VDB Entry
• http://www.securityfocus.com/bid/102032Third Party Advisory, VDB Entry
• http://www.securitytracker.com/id/1040020Third Party Advisory, VDB Entry
• https://access.redhat.com/errata/RHSA-2018:0180Third Party Advisory
• https://medium.com/bindecy/huge-dirty-cow-cve-2017-1000405-110eca132de0Exploit, Issue Tracking, Third Party Advisory
• https://source.android.com/security/bulletin/pixel/2018-02-01Third Party Advisory
• https://www.exploit-db.com/exploits/43199/Exploit, Issue Tracking, Third Party Advisory, VDB Entry

Published

Nov 30, 2017

Last Modified

Jun 17, 2026

Status

Modified