| Revision Date: | 2017-11-30 | Version: | 1 | | Title: | CVE-2017-1000405 on Ubuntu 14.04 LTS (trusty) - high. | | 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. It was discovered that the Linux kernel did not properly handle copy-on- write of transparent huge pages. A local attacker could use this to cause a denial of service (application crashes) or possibly gain administrative privileges.
| | Family: | unix | Class: | vulnerability | | Status: | | Reference(s): | CVE-2017-1000405
| | Platform(s): | Ubuntu 14.04 LTS
| Product(s): | | | Definition Synopsis | | Ubuntu 14.04 LTS (trusty) is installed. AND Package Information
The 'linux' package in trusty was vulnerable but has been fixed (note: '3.13.0-137.186').
OR The 'linux-aws' package in trusty was vulnerable but has been fixed (note: '4.4.0-1005.5').
OR NOT While related to the CVE in some way, the 'linux-azure' package in trusty is not affected (note: '4.15.0-1023.24~14.04.1').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'end-of-life').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'was needs-triage now end-of-life').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'end-of-life').
OR The 'linux-lts-xenial' package in trusty was vulnerable but has been fixed (note: '4.4.0-103.126~14.04.1').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
OR While related to the CVE in some way, a decision has been made to ignore it (note: 'abandoned').
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