From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- include/kvm/arm_psci.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 include/kvm/arm_psci.h (limited to 'include/kvm/arm_psci.h') diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h new file mode 100644 index 000000000..cbaec804e --- /dev/null +++ b/include/kvm/arm_psci.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2012,2013 - ARM Ltd + * Author: Marc Zyngier + */ + +#ifndef __KVM_ARM_PSCI_H__ +#define __KVM_ARM_PSCI_H__ + +#include +#include + +#define KVM_ARM_PSCI_0_1 PSCI_VERSION(0, 1) +#define KVM_ARM_PSCI_0_2 PSCI_VERSION(0, 2) +#define KVM_ARM_PSCI_1_0 PSCI_VERSION(1, 0) +#define KVM_ARM_PSCI_1_1 PSCI_VERSION(1, 1) +#define KVM_ARM_PSCI_1_2 PSCI_VERSION(1, 2) +#define KVM_ARM_PSCI_1_3 PSCI_VERSION(1, 3) + +#define KVM_ARM_PSCI_LATEST KVM_ARM_PSCI_1_3 + +static inline int kvm_psci_version(struct kvm_vcpu *vcpu) +{ + /* + * Our PSCI implementation stays the same across versions from + * v0.2 onward, only adding the few mandatory functions (such + * as FEATURES with 1.0) that are required by newer + * revisions. It is thus safe to return the latest, unless + * userspace has instructed us otherwise. + */ + if (vcpu_has_feature(vcpu, KVM_ARM_VCPU_PSCI_0_2)) { + if (vcpu->kvm->arch.psci_version) + return vcpu->kvm->arch.psci_version; + + return KVM_ARM_PSCI_LATEST; + } + + return KVM_ARM_PSCI_0_1; +} + + +int kvm_psci_call(struct kvm_vcpu *vcpu); + +#endif /* __KVM_ARM_PSCI_H__ */ -- cgit v1.3.1