| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-46977: KVM: VMX: Disable preemption when probing user return MSRs |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: VMX: Disable preemption when probing user return MSRs |
| |
| Disable preemption when probing a user return MSR via RDSMR/WRMSR. If |
| the MSR holds a different value per logical CPU, the WRMSR could corrupt |
| the host's value if KVM is preempted between the RDMSR and WRMSR, and |
| then rescheduled on a different CPU. |
| |
| Opportunistically land the helper in common x86, SVM will use the helper |
| in a future commit. |
| |
| The Linux kernel CVE team has assigned CVE-2021-46977 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.5 with commit 4be5341026246870818e28b53202b001426a5aec and fixed in 5.10.38 with commit 31f29749ee970c251b3a7e5b914108425940d089 |
| Issue introduced in 5.5 with commit 4be5341026246870818e28b53202b001426a5aec and fixed in 5.11.22 with commit 5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94 |
| Issue introduced in 5.5 with commit 4be5341026246870818e28b53202b001426a5aec and fixed in 5.12.5 with commit e3ea1895df719c4ef87862501bb10d95f4177bed |
| Issue introduced in 5.5 with commit 4be5341026246870818e28b53202b001426a5aec and fixed in 5.13 with commit 5104d7ffcf24749939bea7fdb5378d186473f890 |
| |
| 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-2021-46977 |
| 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_host.h |
| arch/x86/kvm/vmx/vmx.c |
| arch/x86/kvm/x86.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/31f29749ee970c251b3a7e5b914108425940d089 |
| https://git.kernel.org/stable/c/5adcdeb57007ccf8ab7ac20bf787ffb6fafb1a94 |
| https://git.kernel.org/stable/c/e3ea1895df719c4ef87862501bb10d95f4177bed |
| https://git.kernel.org/stable/c/5104d7ffcf24749939bea7fdb5378d186473f890 |
