On Intel CPUs sysret to non-canonical address causes a fault on the sysret instruction itself after the stack pointer is set to guest value but before the CPL is changed. Systems running on AMD CPUs are not vulnerable to this issue as sysret on AMD CPUs does not generate a fault before the CPL change.

On Xen, a privileged user on a 64 bit PV guest kernel running on a 64 bit hypervisor could use this flaw to escalate privileges to that of the host. Depending on the particular guest kernel it is also possible that non-privileged guest users could also elevate their privileges to that of the host.

For Red Hat Enterprise Linux guests, only privileged guest users can exploit this issue. HVM guests and 32-bit PV guests cannot be used to exploit this issue.

Acknowledgements:

Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Rafal Wojtczuk as the original reporter.

An exploitable denial of service exists in the Joyent SmartOS 20161110T013148Z Hyprlofs file system. The vulnerability is present in the Ioctl system call with the command HYPRLOFSADDENTRIES. An attacker can cause a buffer to be allocated and never freed. When repeatedly exploited this will result in memory exhaustion, resulting in a full system denial of service.

A double free in the IP management daemon (ipmgmtd) of OmniOS and SmartOS allows a local user to crash the daemon. When authorizing a door request that modifies interface configuration, ipmgmthandler() in usr/src/cmd/cmd-inet/lib/ipmgmtd/ipmgmtdoor.c frees the caller's credential with ucredfree() immediately after reading the user ID, and frees it a second time on the error path if the authorization check fails. An unprivileged local user who does not hold the solaris.network.interface.config authorization can send such a request, for example IPMGMTCMDRESETIF, to the ipmgmtd door, causing ipmgmtd to abort; repeated requests place the svc:/network/ip-interface-management service into maintenance, preventing IP interface configuration. The early free was introduced in 2014 to support lx-branded zones (OmniOS commit 4c170900) and is not present in upstream illumos-gate. It affects OmniOS r151020 and later, and SmartOS, prior to the fix.