| 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-2022-48727: KVM: arm64: Avoid consuming a stale esr value when SError occur |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| KVM: arm64: Avoid consuming a stale esr value when SError occur |
| |
| When any exception other than an IRQ occurs, the CPU updates the ESR_EL2 |
| register with the exception syndrome. An SError may also become pending, |
| and will be synchronised by KVM. KVM notes the exception type, and whether |
| an SError was synchronised in exit_code. |
| |
| When an exception other than an IRQ occurs, fixup_guest_exit() updates |
| vcpu->arch.fault.esr_el2 from the hardware register. When an SError was |
| synchronised, the vcpu esr value is used to determine if the exception |
| was due to an HVC. If so, ELR_EL2 is moved back one instruction. This |
| is so that KVM can process the SError first, and re-execute the HVC if |
| the guest survives the SError. |
| |
| But if an IRQ synchronises an SError, the vcpu's esr value is stale. |
| If the previous non-IRQ exception was an HVC, KVM will corrupt ELR_EL2, |
| causing an unrelated guest instruction to be executed twice. |
| |
| Check ARM_EXCEPTION_CODE() before messing with ELR_EL2, IRQs don't |
| update this register so don't need to check. |
| |
| The Linux kernel CVE team has assigned CVE-2022-48727 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.11 with commit defe21f49bc98b095300752aa1e19bb608f3e97d and fixed in 5.15.22 with commit e1e852746997500f1873f60b954da5f02cc2dba3 |
| Issue introduced in 5.11 with commit defe21f49bc98b095300752aa1e19bb608f3e97d and fixed in 5.16.8 with commit 57e2986c3b25092691a6e3d6ee9168caf8978932 |
| Issue introduced in 5.11 with commit defe21f49bc98b095300752aa1e19bb608f3e97d and fixed in 5.17 with commit 1c71dbc8a179d99dd9bb7e7fc1888db613cf85de |
| |
| 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-2022-48727 |
| 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/arm64/kvm/hyp/include/hyp/switch.h |
| |
| |
| 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/e1e852746997500f1873f60b954da5f02cc2dba3 |
| https://git.kernel.org/stable/c/57e2986c3b25092691a6e3d6ee9168caf8978932 |
| https://git.kernel.org/stable/c/1c71dbc8a179d99dd9bb7e7fc1888db613cf85de |
