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Re: CVE request -- linux kernel: overlay: fix permission checking for setattr


From: cve-assign () mitre org
Date: Wed, 23 Dec 2015 16:46:03 -0500 (EST)

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A flaw was found in the overlay filesystem of the Linux kernel which allows
an unprivileged user to change attributes of the files in the overlay,
particularly allowing access to root-only-accessible files like '/etc/shadow'.

https://bugzilla.redhat.com/show_bug.cgi?id=1291329

A security issue was fixed in kernel 4.4-rc4 resolving the bypassing
of filesystem permission checks in overlayfs during the initial
copy_up.

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=acff81ec2c79492b180fade3c2894425cd35a545

Having these two ->setattr() (one to set verbatim copy of metadata,
another to do what overlayfs ->setattr() had been asked to do in the
first place) combined is where it breaks.

Use CVE-2015-8660.

- -- 
CVE assignment team, MITRE CVE Numbering Authority
M/S M300
202 Burlington Road, Bedford, MA 01730 USA
[ PGP key available through http://cve.mitre.org/cve/request_id.html ]
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