intel-iommu: Fix oops in device_to_iommu() when devices not found.

It's possible for a device in the drhd->devices[] array to be NULL if
it wasn't found at boot time, which means we have to check for that
case.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index fd7472f28674..dcda5212f3bb 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -485,7 +485,8 @@ static struct intel_iommu *device_to_iommu(int segment, u8 bus, u8 devfn)
                             drhd->devices[i]->bus->number == bus &&
                             drhd->devices[i]->devfn == devfn)
                                 return drhd->iommu;
-                        if (drhd->devices[i]->subordinate &&
+                        if (drhd->devices[i] &&
+                            drhd->devices[i]->subordinate &&
                             drhd->devices[i]->subordinate->number <= bus &&
                             drhd->devices[i]->subordinate->subordinate >= bus)
                                 return drhd->iommu;