| 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-2021-47255: kvm: LAPIC: Restore guard to prevent illegal APIC register access |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| kvm: LAPIC: Restore guard to prevent illegal APIC register access |
| |
| Per the SDM, "any access that touches bytes 4 through 15 of an APIC |
| register may cause undefined behavior and must not be executed." |
| Worse, such an access in kvm_lapic_reg_read can result in a leak of |
| kernel stack contents. Prior to commit 01402cf81051 ("kvm: LAPIC: |
| write down valid APIC registers"), such an access was explicitly |
| disallowed. Restore the guard that was removed in that commit. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47255 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.3 with commit 01402cf81051f796dac7c60ca11d6147153ca46a and fixed in 5.4.128 with commit bf99ea52970caeb4583bdba1192c1f9b53b12c84 |
| Issue introduced in 5.3 with commit 01402cf81051f796dac7c60ca11d6147153ca46a and fixed in 5.10.46 with commit 018685461a5b9a9a70e664ac77aef0d7415a3fd5 |
| Issue introduced in 5.3 with commit 01402cf81051f796dac7c60ca11d6147153ca46a and fixed in 5.12.13 with commit a2aff09807fbe4018c269d3773a629949058b210 |
| Issue introduced in 5.3 with commit 01402cf81051f796dac7c60ca11d6147153ca46a and fixed in 5.13 with commit 218bf772bddd221489c38dde6ef8e917131161f6 |
| |
| 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-2021-47255 |
| 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/lapic.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/bf99ea52970caeb4583bdba1192c1f9b53b12c84 |
| https://git.kernel.org/stable/c/018685461a5b9a9a70e664ac77aef0d7415a3fd5 |
| https://git.kernel.org/stable/c/a2aff09807fbe4018c269d3773a629949058b210 |
| https://git.kernel.org/stable/c/218bf772bddd221489c38dde6ef8e917131161f6 |
