KVM: Use memdup_user instead of kmalloc/copy_from_user

Switch to using memdup_user when possible. This makes code more
smaller and compact, and prevents errors.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 35 insertions, 47 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 03042d60a8fc..0a646e2b57c5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1309,12 +1309,11 @@ static int xen_hvm_config(struct kvm_vcpu *vcpu, u64 data)
         if (page_num >= blob_size)
                 goto out;
         r = -ENOMEM;
-        page = kzalloc(PAGE_SIZE, GFP_KERNEL);
-        if (!page)
+        page = memdup_user(blob_addr + (page_num * PAGE_SIZE), PAGE_SIZE);
+        if (IS_ERR(page)) {
+                r = PTR_ERR(page);
                 goto out;
-        r = -EFAULT;
-        if (copy_from_user(page, blob_addr + (page_num * PAGE_SIZE), PAGE_SIZE))
-                goto out_free;
+        }
         if (kvm_write_guest(kvm, page_addr, page, PAGE_SIZE))
                 goto out_free;
         r = 0;
@@ -1988,15 +1987,12 @@ static int msr_io(struct kvm_vcpu *vcpu, struct kvm_msrs __user *user_msrs,
         if (msrs.nmsrs >= MAX_IO_MSRS)
                 goto out;
 
-        r = -ENOMEM;
         size = sizeof(struct kvm_msr_entry) * msrs.nmsrs;
-        entries = kmalloc(size, GFP_KERNEL);
-        if (!entries)
+        entries = memdup_user(user_msrs->entries, size);
+        if (IS_ERR(entries)) {
+                r = PTR_ERR(entries);
                 goto out;
-
-        r = -EFAULT;
-        if (copy_from_user(entries, user_msrs->entries, size))
-                goto out_free;
+        }
 
         r = n = __msr_io(vcpu, &msrs, entries, do_msr);
         if (r < 0)
@@ -2533,13 +2529,12 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = -EINVAL;
                 if (!vcpu->arch.apic)
                         goto out;
-                u.lapic = kmalloc(sizeof(struct kvm_lapic_state), GFP_KERNEL);
-                r = -ENOMEM;
-                if (!u.lapic)
-                        goto out;
-                r = -EFAULT;
-                if (copy_from_user(u.lapic, argp, sizeof(struct kvm_lapic_state)))
+                u.lapic = memdup_user(argp, sizeof(*u.lapic));
+                if (IS_ERR(u.lapic)) {
+                        r = PTR_ERR(u.lapic);
                         goto out;
+                }
+
                 r = kvm_vcpu_ioctl_set_lapic(vcpu, u.lapic);
                 if (r)
                         goto out;
@@ -2718,14 +2713,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 break;
         }
         case KVM_SET_XSAVE: {
-                u.xsave = kzalloc(sizeof(struct kvm_xsave), GFP_KERNEL);
-                r = -ENOMEM;
-                if (!u.xsave)
-                        break;
-
-                r = -EFAULT;
-                if (copy_from_user(u.xsave, argp, sizeof(struct kvm_xsave)))
-                        break;
+                u.xsave = memdup_user(argp, sizeof(*u.xsave));
+                if (IS_ERR(u.xsave)) {
+                        r = PTR_ERR(u.xsave);
+                        goto out;
+                }
 
                 r = kvm_vcpu_ioctl_x86_set_xsave(vcpu, u.xsave);
                 break;
@@ -2746,15 +2738,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 break;
         }
         case KVM_SET_XCRS: {
-                u.xcrs = kzalloc(sizeof(struct kvm_xcrs), GFP_KERNEL);
-                r = -ENOMEM;
-                if (!u.xcrs)
-                        break;
-
-                r = -EFAULT;
-                if (copy_from_user(u.xcrs, argp,
-                                   sizeof(struct kvm_xcrs)))
-                        break;
+                u.xcrs = memdup_user(argp, sizeof(*u.xcrs));
+                if (IS_ERR(u.xcrs)) {
+                        r = PTR_ERR(u.xcrs);
+                        goto out;
+                }
 
                 r = kvm_vcpu_ioctl_x86_set_xcrs(vcpu, u.xcrs);
                 break;
@@ -3190,14 +3178,14 @@ long kvm_arch_vm_ioctl(struct file *filp,
         }
         case KVM_GET_IRQCHIP: {
                 /* 0: PIC master, 1: PIC slave, 2: IOAPIC */
-                struct kvm_irqchip *chip = kmalloc(sizeof(*chip), GFP_KERNEL);
+                struct kvm_irqchip *chip;
 
-                r = -ENOMEM;
-                if (!chip)
+                chip = memdup_user(argp, sizeof(*chip));
+                if (IS_ERR(chip)) {
+                        r = PTR_ERR(chip);
                         goto out;
-                r = -EFAULT;
-                if (copy_from_user(chip, argp, sizeof *chip))
-                        goto get_irqchip_out;
+                }
+
                 r = -ENXIO;
                 if (!irqchip_in_kernel(kvm))
                         goto get_irqchip_out;
@@ -3216,14 +3204,14 @@ long kvm_arch_vm_ioctl(struct file *filp,
         }
         case KVM_SET_IRQCHIP: {
                 /* 0: PIC master, 1: PIC slave, 2: IOAPIC */
-                struct kvm_irqchip *chip = kmalloc(sizeof(*chip), GFP_KERNEL);
+                struct kvm_irqchip *chip;
 
-                r = -ENOMEM;
-                if (!chip)
+                chip = memdup_user(argp, sizeof(*chip));
+                if (IS_ERR(chip)) {
+                        r = PTR_ERR(chip);
                         goto out;
-                r = -EFAULT;
-                if (copy_from_user(chip, argp, sizeof *chip))
-                        goto set_irqchip_out;
+                }
+
                 r = -ENXIO;
                 if (!irqchip_in_kernel(kvm))
                         goto set_irqchip_out;