[PATCH 2/2] KVM: PPC: Fix kvm_arch_vcpu_ioctl vcpu_load leak

[Nicholas Piggin]

vcpu_put is not called if the user copy fails. This can result in preempt
notifier corruption and crashes, among other issues.

Reported-by: Alexey Kardashevskiy <a...@ozlabs.ru>
Fixes: b3cebfe8c1ca ("KVM: PPC: Move vcpu_load/vcpu_put down to each ioctl case 
in kvm_arch_vcpu_ioctl")
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
 arch/powerpc/kvm/powerpc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index be33b5321a76..b4e6f70b97b9 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -2048,9 +2048,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
        {
                struct kvm_enable_cap cap;
                r = -EFAULT;
-               vcpu_load(vcpu);
                if (copy_from_user(&cap, argp, sizeof(cap)))
                        goto out;
+               vcpu_load(vcpu);
                r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
                vcpu_put(vcpu);
                break;
@@ -2074,9 +2074,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
        case KVM_DIRTY_TLB: {
                struct kvm_dirty_tlb dirty;
                r = -EFAULT;
-               vcpu_load(vcpu);
                if (copy_from_user(&dirty, argp, sizeof(dirty)))
                        goto out;
+               vcpu_load(vcpu);
                r = kvm_vcpu_ioctl_dirty_tlb(vcpu, &dirty);
                vcpu_put(vcpu);
                break;
-- 
2.23.0