DescriptionThe collect_mounts function in fs/namespace.c in the Linux kernel before 4.0.5 does not properly consider that it may execute after a path has been unmounted, which allows local users to cause a denial of service (system crash) by leveraging user-namespace root access for an MNT_DETACH umount2 system call.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium (attack range: local)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)wheezy3.2.78-1fixed
wheezy (security)3.2.96-3fixed
jessie (security)3.16.51-3+deb8u1fixed
stretch (security), stretch4.9.82-1+deb9u3fixed
buster, sid4.15.4-1fixed

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

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsource(unstable)(not affected)
linux-2.6source(unstable)(not affected)


- linux <not-affected> (Commit was applied to 4.0.2 as well but fixed in Debian by two subsequent commits)
Debian both applies "mnt: Fail collect_mounts when applied to unmounted mounts"
and "fs_pin: Allow for the possibility that m_list or s_list go unused." in
- linux-2.6 <not-affected> (Introduced and fixed in 4.1-rc1 upstream)
Introduced by: (v4.1-rc1)
Fixed by: (v4.1-rc1)

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