From: Markus Elfring <elfr...@users.sourceforge.net>
Date: Sun, 22 Jan 2017 13:45:18 +0100

* A local variable was set to an error code before a concrete error
  situation was detected. Thus move the corresponding assignments
  into if branches to indicate a software failure there.

  This issue was detected by using the Coccinelle software.

* Return directly after a call of the function "copy_from_user"
  (or two other checks) failed in a case block.

* Delete the jump label "out" and two zero assignments which became
  unnecessary with this refactoring.

Signed-off-by: Markus Elfring <elfr...@users.sourceforge.net>
---
 virt/kvm/kvm_main.c | 66 ++++++++++++++++++-----------------------------------
 1 file changed, 22 insertions(+), 44 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index eeb340708d97..2773e5012948 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2960,20 +2960,17 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_SET_USER_MEMORY_REGION: {
                struct kvm_userspace_memory_region kvm_userspace_mem;
 
-               r = -EFAULT;
                if (copy_from_user(&kvm_userspace_mem, argp,
                                                sizeof(kvm_userspace_mem)))
-                       goto out;
-
+                       return -EFAULT;
                r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem);
                break;
        }
        case KVM_GET_DIRTY_LOG: {
                struct kvm_dirty_log log;
 
-               r = -EFAULT;
                if (copy_from_user(&log, argp, sizeof(log)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
                break;
        }
@@ -2981,18 +2978,16 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_REGISTER_COALESCED_MMIO: {
                struct kvm_coalesced_mmio_zone zone;
 
-               r = -EFAULT;
                if (copy_from_user(&zone, argp, sizeof(zone)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_vm_ioctl_register_coalesced_mmio(kvm, &zone);
                break;
        }
        case KVM_UNREGISTER_COALESCED_MMIO: {
                struct kvm_coalesced_mmio_zone zone;
 
-               r = -EFAULT;
                if (copy_from_user(&zone, argp, sizeof(zone)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_vm_ioctl_unregister_coalesced_mmio(kvm, &zone);
                break;
        }
@@ -3000,18 +2995,16 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_IRQFD: {
                struct kvm_irqfd data;
 
-               r = -EFAULT;
                if (copy_from_user(&data, argp, sizeof(data)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_irqfd(kvm, &data);
                break;
        }
        case KVM_IOEVENTFD: {
                struct kvm_ioeventfd data;
 
-               r = -EFAULT;
                if (copy_from_user(&data, argp, sizeof(data)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_ioeventfd(kvm, &data);
                break;
        }
@@ -3019,9 +3012,8 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_SIGNAL_MSI: {
                struct kvm_msi msi;
 
-               r = -EFAULT;
                if (copy_from_user(&msi, argp, sizeof(msi)))
-                       goto out;
+                       return -EFAULT;
                r = kvm_send_userspace_msi(kvm, &msi);
                break;
        }
@@ -3031,22 +3023,17 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_IRQ_LINE: {
                struct kvm_irq_level irq_event;
 
-               r = -EFAULT;
                if (copy_from_user(&irq_event, argp, sizeof(irq_event)))
-                       goto out;
+                       return -EFAULT;
 
                r = kvm_vm_ioctl_irq_line(kvm, &irq_event,
                                        ioctl == KVM_IRQ_LINE_STATUS);
                if (r)
-                       goto out;
-
-               r = -EFAULT;
-               if (ioctl == KVM_IRQ_LINE_STATUS) {
-                       if (copy_to_user(argp, &irq_event, sizeof(irq_event)))
-                               goto out;
-               }
+                       return r;
 
-               r = 0;
+               if (ioctl == KVM_IRQ_LINE_STATUS &&
+                   copy_to_user(argp, &irq_event, sizeof(irq_event)))
+                       return -EFAULT;
                break;
        }
 #endif
@@ -3056,24 +3043,20 @@ static long kvm_vm_ioctl(struct file *filp,
                struct kvm_irq_routing __user *urouting;
                struct kvm_irq_routing_entry *entries = NULL;
 
-               r = -EFAULT;
                if (copy_from_user(&routing, argp, sizeof(routing)))
-                       goto out;
-               r = -EINVAL;
-               if (routing.nr > KVM_MAX_IRQ_ROUTES)
-                       goto out;
-               if (routing.flags)
-                       goto out;
+                       return -EFAULT;
+               if (routing.nr > KVM_MAX_IRQ_ROUTES || routing.flags)
+                       return -EINVAL;
                if (routing.nr) {
-                       r = -ENOMEM;
                        entries = vmalloc(routing.nr * sizeof(*entries));
                        if (!entries)
-                               goto out;
-                       r = -EFAULT;
+                               return -ENOMEM;
                        urouting = argp;
                        if (copy_from_user(entries, urouting->entries,
-                                          routing.nr * sizeof(*entries)))
+                                          routing.nr * sizeof(*entries))) {
+                               r = -EFAULT;
                                goto out_free_irq_routing;
+                       }
                }
                r = kvm_set_irq_routing(kvm, entries, routing.nr,
                                        routing.flags);
@@ -3085,19 +3068,15 @@ static long kvm_vm_ioctl(struct file *filp,
        case KVM_CREATE_DEVICE: {
                struct kvm_create_device cd;
 
-               r = -EFAULT;
                if (copy_from_user(&cd, argp, sizeof(cd)))
-                       goto out;
+                       return -EFAULT;
 
                r = kvm_ioctl_create_device(kvm, &cd);
                if (r)
-                       goto out;
+                       return r;
 
-               r = -EFAULT;
                if (copy_to_user(argp, &cd, sizeof(cd)))
-                       goto out;
-
-               r = 0;
+                       return -EFAULT;
                break;
        }
        case KVM_CHECK_EXTENSION:
@@ -3106,7 +3085,6 @@ static long kvm_vm_ioctl(struct file *filp,
        default:
                r = kvm_arch_vm_ioctl(filp, ioctl, arg);
        }
-out:
        return r;
 }
 
-- 
2.11.0

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