Description
arch/x86/kvm/vmx.c in the Linux kernel through 4.6.3 mishandles the APICv on/off state, which allows guest OS users to obtain direct APIC MSR access on the host OS, and consequently cause a denial of service (host OS crash) or possibly execute arbitrary code on the host OS, via x2APIC mode.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 4.5.5-1 | — |
| Debian 13 | linux | 4.5.5-1 | — |
| Debian 12 | linux | 4.5.5-1 | — |
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1337806
- http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3ce424e45411cf5a13105e0386b6ecf6eeb4f66f
- [oss-security] 20160520 CVE-2016-4440 Kernel: kvm: vmx: incorrect state update leading to MSR access mailing-list
- https://github.com/torvalds/linux/commit/3ce424e45411cf5a13105e0386b6ecf6eeb4f66f