FreeBSD VuXML: Documenting security issues in FreeBSD and the FreeBSD Ports Collection

FreeBSD -- Kernel stack disclosure in 4.3BSD compatibility layer

Affected packages
10.3 <= FreeBSD-kernel < 10.3_4
10.2 <= FreeBSD-kernel < 10.2_18
10.1 <= FreeBSD-kernel < 10.1_35
9.3 <= FreeBSD-kernel < 9.3_43


VuXML ID 7cad4795-600a-11e6-a6c3-14dae9d210b8
Discovery 2016-05-31
Entry 2016-08-11

Problem Description:

The implementation of historic stat(2) system call does not clear the output struct before copying it out to userland.


An unprivileged user can read a portion of uninitialised kernel stack data, which may contain sensitive information, such as the stack guard, portions of the file cache or terminal buffers, which an attacker might leverage to obtain elevated privileges.


FreeBSD Advisory SA-16:21.43bsd