| From bippy-7c5fe7eed585 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-2021-47008: KVM: SVM: Make sure GHCB is mapped before updating |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: SVM: Make sure GHCB is mapped before updating |
| |
| Access to the GHCB is mainly in the VMGEXIT path and it is known that the |
| GHCB will be mapped. But there are two paths where it is possible the GHCB |
| might not be mapped. |
| |
| The sev_vcpu_deliver_sipi_vector() routine will update the GHCB to inform |
| the caller of the AP Reset Hold NAE event that a SIPI has been delivered. |
| However, if a SIPI is performed without a corresponding AP Reset Hold, |
| then the GHCB might not be mapped (depending on the previous VMEXIT), |
| which will result in a NULL pointer dereference. |
| |
| The svm_complete_emulated_msr() routine will update the GHCB to inform |
| the caller of a RDMSR/WRMSR operation about any errors. While it is likely |
| that the GHCB will be mapped in this situation, add a safe guard |
| in this path to be certain a NULL pointer dereference is not encountered. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47008 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.11 with commit f1c6366e304328de301be362eca905a3503ff33b and fixed in 5.11.22 with commit fb9e14f4f8217a0980f8da2c8ff70dee058cbe47 |
| Issue introduced in 5.11 with commit f1c6366e304328de301be362eca905a3503ff33b and fixed in 5.12.5 with commit fd722a57fe0b80133dacae4e1c852ee4212f9b2e |
| Issue introduced in 5.11 with commit f1c6366e304328de301be362eca905a3503ff33b and fixed in 5.13 with commit a3ba26ecfb569f4aa3f867e80c02aa65f20aadad |
| |
| 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-2021-47008 |
| 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/kvm/svm/sev.c |
| arch/x86/kvm/svm/svm.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/fb9e14f4f8217a0980f8da2c8ff70dee058cbe47 |
| https://git.kernel.org/stable/c/fd722a57fe0b80133dacae4e1c852ee4212f9b2e |
| https://git.kernel.org/stable/c/a3ba26ecfb569f4aa3f867e80c02aa65f20aadad |
