diff options
| author | Paolo Bonzini | 2023-04-21 19:19:02 -0400 |
|---|---|---|
| committer | Paolo Bonzini | 2023-04-21 19:19:02 -0400 |
| commit | 265b97cbc22e0f67f79a71443b60dc1237ca5ee6 (patch) | |
| tree | fb42627096d8efe1e76a482a66cc13fac76e7ca4 | |
| parent | 0bf9601f8ef0703523018e975d6c1f3fdfcff4b9 (diff) | |
| parent | a25bc8486f9c01c1af6b6c5657234b2eee2c39d6 (diff) | |
Merge tag 'kvmarm-fixes-6.3-4' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 fixes for 6.3, part #4
- Plug a buffer overflow due to the use of the user-provided register
width for firmware regs. Outright reject accesses where the
user register width does not match the kernel representation.
- Protect non-atomic RMW operations on vCPU flags against preemption,
as an update to the flags by an intervening preemption could be lost.
| -rw-r--r-- | arch/arm64/include/asm/kvm_host.h | 19 | ||||
| -rw-r--r-- | arch/arm64/kvm/hypercalls.c | 2 |
2 files changed, 20 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index bcd774d74f34..3dd691c85ca0 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -576,9 +576,22 @@ struct kvm_vcpu_arch { ({ \ __build_check_flag(v, flagset, f, m); \ \ - v->arch.flagset & (m); \ + READ_ONCE(v->arch.flagset) & (m); \ }) +/* + * Note that the set/clear accessors must be preempt-safe in order to + * avoid nesting them with load/put which also manipulate flags... + */ +#ifdef __KVM_NVHE_HYPERVISOR__ +/* the nVHE hypervisor is always non-preemptible */ +#define __vcpu_flags_preempt_disable() +#define __vcpu_flags_preempt_enable() +#else +#define __vcpu_flags_preempt_disable() preempt_disable() +#define __vcpu_flags_preempt_enable() preempt_enable() +#endif + #define __vcpu_set_flag(v, flagset, f, m) \ do { \ typeof(v->arch.flagset) *fset; \ @@ -586,9 +599,11 @@ struct kvm_vcpu_arch { __build_check_flag(v, flagset, f, m); \ \ fset = &v->arch.flagset; \ + __vcpu_flags_preempt_disable(); \ if (HWEIGHT(m) > 1) \ *fset &= ~(m); \ *fset |= (f); \ + __vcpu_flags_preempt_enable(); \ } while (0) #define __vcpu_clear_flag(v, flagset, f, m) \ @@ -598,7 +613,9 @@ struct kvm_vcpu_arch { __build_check_flag(v, flagset, f, m); \ \ fset = &v->arch.flagset; \ + __vcpu_flags_preempt_disable(); \ *fset &= ~(m); \ + __vcpu_flags_preempt_enable(); \ } while (0) #define vcpu_get_flag(v, ...) __vcpu_get_flag((v), __VA_ARGS__) diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 5da884e11337..c4b4678bc4a4 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -397,6 +397,8 @@ int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) u64 val; int wa_level; + if (KVM_REG_SIZE(reg->id) != sizeof(val)) + return -ENOENT; if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id))) return -EFAULT; |