CVE-2017-1000405

NameCVE-2017-1000405
DescriptionThe 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SuSE, Mageia, GitHub code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)wheezy3.2.78-1fixed
wheezy (security)3.2.96-2fixed
jessie3.16.51-2fixed
jessie (security)3.16.43-2+deb8u5vulnerable
stretch4.9.65-3fixed
stretch (security)4.9.30-2+deb9u5vulnerable
buster4.13.13-1vulnerable
sid4.14.2-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsource(unstable)4.14.2-1
linuxsourcejessie3.16.51-1
linuxsourcestretch4.9.65-1
linuxsourcewheezy(not affected)

Notes

[wheezy] - linux <not-affected> (vulnerable code not present, cf. kernel-sec information)
Fixed by: https://git.kernel.org/linus/a8f97366452ed491d13cf1e44241bc0b5740b1f0
http://www.openwall.com/lists/oss-security/2017/11/30/1
https://github.com/bindecy/HugeDirtyCowPOC

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