CVE-2018-13405

The inode_init_owner function in fs/inode.c in the Linux kernel through
3.16 allows local users to create files with an unintended group ownership,
in a scenario where a directory is SGID to a certain group and is writable
by a user who is not a member of that group. Here, the non-member can
trigger creation of a plain file whose group ownership is that group. The
intended behavior was that the non-member can trigger creation of a
directory (but not a plain file) whose group ownership is that group. The
non-member can escalate privileges by making the plain file executable and
SGID.

Bugs

• <https://launchpad.net/bugs/1779923&gt;

Notes