Jul 22 2008

KVM: ia64: Fix irq disabling leak in error handling code 

Author: Julia Lawall <julia@diku.dk>

There is a call to local_irq_restore in the normal exit case, so it would
seem that there should be one on an error return as well.

The semantic patch that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// 
@@
expression l;
expression E,E1,E2;
@@

local_irq_save(l);
... when != local_irq_restore(l)
    when != spin_unlock_irqrestore(E,l)
    when any
    when strict
(
if (...) { ... when != local_irq_restore(l)
               when != spin_unlock_irqrestore(E1,l)
+   local_irq_restore(l);
    return ...;
}
|
if (...)
+   {local_irq_restore(l);
    return ...;
+   }
|
spin_unlock_irqrestore(E2,l);
|
local_irq_restore(l);
)
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Avi Kivity 

---
 arch/ia64/kvm/kvm-ia64.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
 
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 2672f4d..7a37d06 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -125,9 +125,9 @@ void kvm_arch_hardware_enable(void *garbage)
 				PAGE_KERNEL));
 	local_irq_save(saved_psr);
 	slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
+	local_irq_restore(saved_psr);
 	if (slot < 0)
 		return;
-	local_irq_restore(saved_psr);
 
 	spin_lock(&vp_lock);
 	status = ia64_pal_vp_init_env(kvm_vsa_base ?
@@ -160,9 +160,9 @@ void kvm_arch_hardware_disable(void *garbage)
 
 	local_irq_save(saved_psr);
 	slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
+	local_irq_restore(saved_psr);
 	if (slot < 0)
 		return;
-	local_irq_restore(saved_psr);
 
 	status = ia64_pal_vp_exit_env(host_iva);
 	if (status)
@@ -1253,6 +1253,7 @@ static int vti_vcpu_setup(struct kvm_vcpu *vcpu, int id)
 uninit:
 	kvm_vcpu_uninit(vcpu);
 fail:
+	local_irq_restore(psr);
 	return r;
 }

qlambert