Changelog
amd64-microcode (1.20160316.1) oldstable; urgency=critical
* Upstream release 20160316 built from linux-firmware:
+ Updated Microcodes:
sig 0x00600f20, patch id 0x0600084f, 2016-01-25
+ This microcode updates fixes a critical erratum on NMI handling
introduced by microcode patch id 0x6000832 from the 20141028 update.
The erratum is also present on microcode patch id 0x6000836.
+ THIS IS A CRITICAL STABILITY AND SECURITY UPDATE FOR THE EARLIER
AMD PILEDRIVER PROCESSORS, including:
+ AMD Opteron 3300, 4300, 6300
+ AMD FX "Vishera" (43xx, 63xx, 83xx, 93xx, 95xx)
+ AMD processors with family 21, model 2, stepping 0
* Robert Święcki, while fuzzing the kernel using the syzkaller tool,
uncovered very strange behavior on an AMD FX-8320, later reproduced on
other AMD Piledriver model 2, stepping 0 processors including the Opteron
6300. Robert discovered, using his proof-of-concept exploit code, that
the incorrect behavior allows an unpriviledged attacker on an unpriviledged
VM to corrupt the return stack of the host kernel's NMI handler. At best,
this results in unpredictable host behavior. At worst, it allows for an
unpriviledged user on unpriviledged VM to carry a sucessful host-kernel
ring 0 code injection attack.
* The erratum is timing-dependant, easily triggered by workloads that
cause a high number of NMIs, such as running the "perf" tool.
-- Henrique de Moraes Holschuh <email address hidden> Sat, 19 Mar 2016 19:10:20 -0300
