KVM: nSVM: Replace kzalloc() + copy_from_user() with memdup_user()

Replace kzalloc() followed by copy_from_user() with memdup_user() to
improve and simplify svm_set_nested_state().

Return early if an error occurs instead of trying to allocate memory for
'save' when memory allocation for 'ctl' already failed.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Link: https://lore.kernel.org/r/20250903002951.118912-1-thorsten.blum@linux.dev
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b7fd2e869998751fbd6accf3b4b060f907ff9019..826473f2d7c7e47c942e958b46f2327840ccaaaf 100644 (file)
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1798,17 +1798,15 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu,
        if (kvm_state->size < sizeof(*kvm_state) + KVM_STATE_NESTED_SVM_VMCB_SIZE)
                return -EINVAL;
 
-       ret  = -ENOMEM;
-       ctl  = kzalloc(sizeof(*ctl),  GFP_KERNEL);
-       save = kzalloc(sizeof(*save), GFP_KERNEL);
-       if (!ctl || !save)
-               goto out_free;
-
-       ret = -EFAULT;
-       if (copy_from_user(ctl, &user_vmcb->control, sizeof(*ctl)))
-               goto out_free;
-       if (copy_from_user(save, &user_vmcb->save, sizeof(*save)))
-               goto out_free;
+       ctl = memdup_user(&user_vmcb->control, sizeof(*ctl));
+       if (IS_ERR(ctl))
+               return PTR_ERR(ctl);
+
+       save = memdup_user(&user_vmcb->save, sizeof(*save));
+       if (IS_ERR(save)) {
+               kfree(ctl);
+               return PTR_ERR(save);
+       }
 
        ret = -EINVAL;
        __nested_copy_vmcb_control_to_cache(vcpu, &ctl_cached, ctl);