| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47110: x86/kvm: Disable kvmclock on all CPUs on shutdown |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| x86/kvm: Disable kvmclock on all CPUs on shutdown |
| |
| Currenly, we disable kvmclock from machine_shutdown() hook and this |
| only happens for boot CPU. We need to disable it for all CPUs to |
| guard against memory corruption e.g. on restore from hibernate. |
| |
| Note, writing '0' to kvmclock MSR doesn't clear memory location, it |
| just prevents hypervisor from updating the location so for the short |
| while after write and while CPU is still alive, the clock remains usable |
| and correct so we don't need to switch to some other clocksource. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47110 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 2.6.26 with commit 1e977aa12dd4f80688b1f243762212e75c6d7fe8 and fixed in 5.4.125 with commit 9084fe1b3572664ad276f427dce575f580c9799a |
| Issue introduced in 2.6.26 with commit 1e977aa12dd4f80688b1f243762212e75c6d7fe8 and fixed in 5.10.43 with commit 3b0becf8b1ecf642a9edaf4c9628ffc641e490d6 |
| Issue introduced in 2.6.26 with commit 1e977aa12dd4f80688b1f243762212e75c6d7fe8 and fixed in 5.12.10 with commit 1df2dc09926f61319116c80ee85701df33577d70 |
| Issue introduced in 2.6.26 with commit 1e977aa12dd4f80688b1f243762212e75c6d7fe8 and fixed in 5.13 with commit c02027b5742b5aa804ef08a4a9db433295533046 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2021-47110 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| arch/x86/include/asm/kvm_para.h |
| arch/x86/kernel/kvm.c |
| arch/x86/kernel/kvmclock.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/9084fe1b3572664ad276f427dce575f580c9799a |
| https://git.kernel.org/stable/c/3b0becf8b1ecf642a9edaf4c9628ffc641e490d6 |
| https://git.kernel.org/stable/c/1df2dc09926f61319116c80ee85701df33577d70 |
| https://git.kernel.org/stable/c/c02027b5742b5aa804ef08a4a9db433295533046 |
