Commit 8d2aec3b authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: use u64_to_user_ptr() 



There is no danger to the kernel if 32-bit userspace provides a 64-bit
value that has the high bits set, but for whatever reason happens to
resolve to an address that has something mapped there.  KVM uses the
checked version of get_user() and put_user(), so any faults are caught
properly.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240404121327.3107131-4-pbonzini@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0d7bf5e5

arch/x86/kvm/x86.c

+3 −21
Original line number Diff line number Diff line
@@ -4842,25 +4842,13 @@ 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))
@@ -5712,12 +5700,9 @@ 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;
@@ -5735,13 +5720,10 @@ 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;