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KVM: x86: use u64_to_user_ptr()

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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: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240404121327.3107131-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2024-04-04 08:13:13 -04:00
parent 0d7bf5e5b0
commit 8d2aec3b2d
1 changed files with 3 additions and 21 deletions
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24
arch/x86/kvm/x86.c
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@@ -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;