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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
EUVD |
EUVD-2017-1545 | 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. |
Ubuntu USN |
USN-3507-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-3507-2 | Linux kernel (GCP) vulnerabilities |
Ubuntu USN |
USN-3508-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-3508-2 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-3509-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-3509-2 | Linux kernel (Xenial HWE) vulnerabilities |
Ubuntu USN |
USN-3510-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-3510-2 | Linux kernel (Trusty HWE) vulnerabilities |
Ubuntu USN |
USN-3511-1 | Linux kernel (Azure) vulnerabilities |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Wed, 16 Jul 2025 13:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
epss
|
epss
|
Status: PUBLISHED
Assigner: mitre
Published:
Updated: 2024-08-05T22:00:40.830Z
Reserved: 2017-11-29T00:00:00
Link: CVE-2017-1000405
No data.
Status : Deferred
Published: 2017-11-30T22:29:00.217
Modified: 2025-04-20T01:37:25.860
Link: CVE-2017-1000405
OpenCVE Enrichment
No data.
EUVD
Ubuntu USN