arch/x86/entry/entry_64.S in the Linux kernel before 4.1.6 on the x86_64 platform improperly relies on espfix64 during nested NMI processing, which allows local users to gain privileges by triggering an NMI within a certain instruction window.

Affected: Ubuntu:14.04:LTS: linux

Andy Lutomirski discovered a flaw in the Linux kernel's handling of nested NMIs (non-maskable interrupts). An unprivileged local user could exploit this flaw to cause a denial of service (system crash) or potentially escalate their privileges. (CVE-2015-3290)

Colin King discovered a flaw in the add_key function of the Linux kernel's keyring subsystem. A local user could exploit this flaw to cause a denial of service (memory exhaustion). (CVE-2015-1333)

Andy Lutomirski discovered a flaw that allows user to cause the Linux kernel to ignore some NMIs (non-maskable interrupts). A local unprivileged user could exploit this flaw to potentially cause the system to miss important NMIs resulting in unspecified effects. (CVE-2015-3291)

Andy Lutomirski and Petr Matousek discovered that an NMI (non-maskable interrupt) that interrupts userspace and encounters an IRET fault is incorrectly handled by the Linux kernel. An unprivileged local user could exploit this flaw to cause a denial of service (kernel OOPs), corruption, or potentially escalate privileges on the system. (CVE-2015-5157)