diff --git a/common/lib/kernel/pci.cpp b/common/lib/kernel/pci.cpp
index 53ebd1f77..fcdd34dab 100644
--- a/common/lib/kernel/pci.cpp
+++ b/common/lib/kernel/pci.cpp
@@ -376,7 +376,10 @@ int
 Device::getIOMMUGroup() const
 {
 	int ret;
-	char *group, link[1024], sysfs[1024];
+	char *group;
+	//readlink does not add a null terminator!
+	char link[1024] = {0};
+	char sysfs[1024];
 
 	snprintf(sysfs, sizeof(sysfs), "%s/bus/pci/devices/%04x:%02x:%02x.%x/iommu_group", SYSFS_PATH,
 		slot.domain, slot.bus, slot.device, slot.function);
diff --git a/common/lib/kernel/vfio.cpp b/common/lib/kernel/vfio.cpp
index f209b506e..b71995f55 100644
--- a/common/lib/kernel/vfio.cpp
+++ b/common/lib/kernel/vfio.cpp
@@ -604,6 +604,8 @@ Device::pciMsiInit(int efds[])
 	auto *irqSet = reinterpret_cast<struct vfio_irq_set*>(irqSetBuf);
 
 	irqSet->argsz = irqSetSize;
+	// DATA_EVENTFD binds the interrupt to the provided eventfd.
+	// SET_ACTION_TRIGGER enables kernel->userspace signalling.
 	irqSet->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_TRIGGER;
 	irqSet->index = VFIO_PCI_MSI_IRQ_INDEX;
 	irqSet->start = 0;