| 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-2021-47389: KVM: SVM: fix missing sev_decommission in sev_receive_start |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: SVM: fix missing sev_decommission in sev_receive_start |
| |
| DECOMMISSION the current SEV context if binding an ASID fails after |
| RECEIVE_START. Per AMD's SEV API, RECEIVE_START generates a new guest |
| context and thus needs to be paired with DECOMMISSION: |
| |
| The RECEIVE_START command is the only command other than the LAUNCH_START |
| command that generates a new guest context and guest handle. |
| |
| The missing DECOMMISSION can result in subsequent SEV launch failures, |
| as the firmware leaks memory and might not able to allocate more SEV |
| guest contexts in the future. |
| |
| Note, LAUNCH_START suffered the same bug, but was previously fixed by |
| commit 934002cd660b ("KVM: SVM: Call SEV Guest Decommission if ASID |
| binding fails"). |
| |
| The Linux kernel CVE team has assigned CVE-2021-47389 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.13 with commit af43cbbf954b50ca97d5e7bb56c2edc6ffd209ef and fixed in 5.14.10 with commit efd7866e114dcb44f86d151e843f8276b7efbc67 |
| Issue introduced in 5.13 with commit af43cbbf954b50ca97d5e7bb56c2edc6ffd209ef and fixed in 5.15 with commit f1815e0aa770f2127c5df31eb5c2f0e37b60fa77 |
| |
| 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-2021-47389 |
| 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 |
| |
| |
| 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/efd7866e114dcb44f86d151e843f8276b7efbc67 |
| https://git.kernel.org/stable/c/f1815e0aa770f2127c5df31eb5c2f0e37b60fa77 |
