[PATCHv2] kvm: drop parameter validation

[PATCHv2] kvm: drop parameter validation

[Michael S. Tsirkin]

We validate irq pin number when routing is setup, so
code handling illegal irq # in pic and ioapic on each injection
is never called.
Drop it, replace with BUG_ON to catch out of bounds access bugs.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Changes from v1:
        add BUG_ON at Gleb's suggestion

 arch/x86/kvm/i8259.c | 18 +++++++++---------
 virt/kvm/ioapic.c    | 37 +++++++++++++++++++------------------
 2 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index e498b18..90c84f9 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -190,17 +190,17 @@ void kvm_pic_update_irq(struct kvm_pic *s)
 
 int kvm_pic_set_irq(struct kvm_pic *s, int irq, int irq_source_id, int level)
 {
-	int ret = -1;
+	int ret, irq_level;
+
+	BUG_ON(irq < 0 || irq >= PIC_NUM_PINS);
 
 	pic_lock(s);
-	if (irq >= 0 && irq < PIC_NUM_PINS) {
-		int irq_level = __kvm_irq_line_state(&s->irq_states[irq],
-						     irq_source_id, level);
-		ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, irq_level);
-		pic_update_irq(s);
-		trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
-				      s->pics[irq >> 3].imr, ret == 0);
-	}
+	irq_level = __kvm_irq_line_state(&s->irq_states[irq],
+					 irq_source_id, level);
+	ret = pic_set_irq1(&s->pics[irq >> 3], irq & 7, irq_level);
+	pic_update_irq(s);
+	trace_kvm_pic_set_irq(irq >> 3, irq & 7, s->pics[irq >> 3].elcr,
+			      s->pics[irq >> 3].imr, ret == 0);
 	pic_unlock(s);
 
 	return ret;
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index ef61d52..cfb7e4d 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -197,28 +197,29 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int irq_source_id,
 	u32 old_irr;
 	u32 mask = 1 << irq;
 	union kvm_ioapic_redirect_entry entry;
-	int ret = 1;
+	int ret, irq_level;
+
+	BUG_ON(irq < 0 || irq >= IOAPIC_NUM_PINS);
 
 	spin_lock(&ioapic->lock);
 	old_irr = ioapic->irr;
-	if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
-		int irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
-						     irq_source_id, level);
-		entry = ioapic->redirtbl[irq];
-		irq_level ^= entry.fields.polarity;
-		if (!irq_level)
-			ioapic->irr &= ~mask;
-		else {
-			int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
-			ioapic->irr |= mask;
-			if ((edge && old_irr != ioapic->irr) ||
-			    (!edge && !entry.fields.remote_irr))
-				ret = ioapic_service(ioapic, irq);
-			else
-				ret = 0; /* report coalesced interrupt */
-		}
-		trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
+	irq_level = __kvm_irq_line_state(&ioapic->irq_states[irq],
+					 irq_source_id, level);
+	entry = ioapic->redirtbl[irq];
+	irq_level ^= entry.fields.polarity;
+	if (!irq_level) {
+		ioapic->irr &= ~mask;
+		ret = 1;
+	} else {
+		int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG);
+		ioapic->irr |= mask;
+		if ((edge && old_irr != ioapic->irr) ||
+		    (!edge && !entry.fields.remote_irr))
+			ret = ioapic_service(ioapic, irq);
+		else
+			ret = 0; /* report coalesced interrupt */
 	}
+	trace_kvm_ioapic_set_irq(entry.bits, irq, ret == 0);
 	spin_unlock(&ioapic->lock);
 
 	return ret;
-- 
MST

Re: [PATCHv2] kvm: drop parameter validation

[Marcelo Tosatti]

On Tue, Aug 14, 2012 at 07:20:28PM +0300, Michael S. Tsirkin wrote:
> We validate irq pin number when routing is setup, so
> code handling illegal irq # in pic and ioapic on each injection
> is never called.
> Drop it, replace with BUG_ON to catch out of bounds access bugs.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> 
> Changes from v1:
>         add BUG_ON at Gleb's suggestion
> 
>  arch/x86/kvm/i8259.c | 18 +++++++++---------
>  virt/kvm/ioapic.c    | 37 +++++++++++++++++++------------------
>  2 files changed, 28 insertions(+), 27 deletions(-)

Applied, thanks.