There is no danger to the kernel if userspace provides a 64-bit value that
has the high bits set, but for whatever reason happ[ens to resolve to an
address that has something mapped there. KVM uses the checked version
of put_user() in kvm_x86_dev_get_attr().
Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 24 +++---------------------
1 file changed, 3 insertions(+), 21 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f3f7405e0628..14c969782d73 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4791,25 +4791,13 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
return r;
}
-static inline void __user *kvm_get_attr_addr(struct kvm_device_attr *attr)
-{
- void __user *uaddr = (void __user*)(unsigned long)attr->addr;
-
- if ((u64)(unsigned long)uaddr != attr->addr)
- return ERR_PTR_USR(-EFAULT);
- return uaddr;
-}
-
static int kvm_x86_dev_get_attr(struct kvm_device_attr *attr)
{
- u64 __user *uaddr = kvm_get_attr_addr(attr);
+ u64 __user *uaddr = u64_to_user_ptr(attr->addr);
if (attr->group)
return -ENXIO;
- if (IS_ERR(uaddr))
- return PTR_ERR(uaddr);
-
switch (attr->attr) {
case KVM_X86_XCOMP_GUEST_SUPP:
if (put_user(kvm_caps.supported_xcr0, uaddr))
@@ -5664,12 +5652,9 @@ static int kvm_arch_tsc_has_attr(struct kvm_vcpu *vcpu,
static int kvm_arch_tsc_get_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr)
{
- u64 __user *uaddr = kvm_get_attr_addr(attr);
+ u64 __user *uaddr = u64_to_user_ptr(attr->addr);
int r;
- if (IS_ERR(uaddr))
- return PTR_ERR(uaddr);
-
switch (attr->attr) {
case KVM_VCPU_TSC_OFFSET:
r = -EFAULT;
@@ -5687,13 +5672,10 @@ static int kvm_arch_tsc_get_attr(struct kvm_vcpu *vcpu,
static int kvm_arch_tsc_set_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr)
{
- u64 __user *uaddr = kvm_get_attr_addr(attr);
+ u64 __user *uaddr = u64_to_user_ptr(attr->addr);
struct kvm *kvm = vcpu->kvm;
int r;
- if (IS_ERR(uaddr))
- return PTR_ERR(uaddr);
-
switch (attr->attr) {
case KVM_VCPU_TSC_OFFSET: {
u64 offset, tsc, ns;
--
2.39.1
