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Subject[PATCH 39/40] KVM: Reduce stack usage in kvm_arch_vcpu_ioctl()
Date
From: Dave Hansen <dave@linux.vnet.ibm.com>

[sheng: fix KVM_GET_LAPIC using wrong size]

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/kvm/x86.c | 23 +++++++++++++++--------
1 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 87d4342..f1b0223 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1542,28 +1542,33 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
struct kvm_vcpu *vcpu = filp->private_data;
void __user *argp = (void __user *)arg;
int r;
+ struct kvm_lapic_state *lapic = NULL;

switch (ioctl) {
case KVM_GET_LAPIC: {
- struct kvm_lapic_state lapic;
+ lapic = kzalloc(sizeof(struct kvm_lapic_state), GFP_KERNEL);

- memset(&lapic, 0, sizeof lapic);
- r = kvm_vcpu_ioctl_get_lapic(vcpu, &lapic);
+ r = -ENOMEM;
+ if (!lapic)
+ goto out;
+ r = kvm_vcpu_ioctl_get_lapic(vcpu, lapic);
if (r)
goto out;
r = -EFAULT;
- if (copy_to_user(argp, &lapic, sizeof lapic))
+ if (copy_to_user(argp, lapic, sizeof(struct kvm_lapic_state)))
goto out;
r = 0;
break;
}
case KVM_SET_LAPIC: {
- struct kvm_lapic_state lapic;
-
+ lapic = kmalloc(sizeof(struct kvm_lapic_state), GFP_KERNEL);
+ r = -ENOMEM;
+ if (!lapic)
+ goto out;
r = -EFAULT;
- if (copy_from_user(&lapic, argp, sizeof lapic))
+ if (copy_from_user(lapic, argp, sizeof(struct kvm_lapic_state)))
goto out;
- r = kvm_vcpu_ioctl_set_lapic(vcpu, &lapic);;
+ r = kvm_vcpu_ioctl_set_lapic(vcpu, lapic);
if (r)
goto out;
r = 0;
@@ -1661,6 +1666,8 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
r = -EINVAL;
}
out:
+ if (lapic)
+ kfree(lapic);
return r;
}

--
1.6.0.1


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