FreeBSD/amd64 runs on CPUs from different vendors. Due to varying behaviour of CPUs in 64 bit mode a sanity check of the kernel may be insufficient when returning from a system call. Successful exploitation of the problem can lead to local kernel privilege escalation, kernel data corruption and/or crash.
Inj3ct0r team today released related private exploit on their website, which allow normal FreeBSD users to Privilege Escalation. All systems running 64 bit Xen hypervisor running 64 bit PV guests onIntel CPUs are vulnerable to this issue.
However FreeBSD/amd64 running on AMD CPUs is not vulnerable to thisparticular problem.Systems with 64 bit capable CPUs, but running the 32 bit FreeBSD/i386kernel are not vulnerable, nor are systems running on differentprocessor architectures.
Download the relevant patch from the location below:
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret.patch
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret.patch.asc
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret-81.patch
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret-81.patch.asc
[8.1 if original sysret.patch has been applied]
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret-81-correction.patch
# fetch https://security.FreeBSD.org/patches/SA-12:04/sysret-81-correction.patch.asc
How to Apply the patch ?
# cd /usr/src
# patch < /path/to/patch
After Recompile your kernel as described
# freebsd-update fetch
# freebsd-update install