Prevent oops at boot with VT-d

With some broken BIOSs when VT-d is enabled, the data structures are
filled incorrectly. This can cause a NULL pointer dereference in very
early boot.

Signed-off-by: Dirk Hohndel <hohndel@linux.intel.com>
Acked-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c
index 235fb7a5a8a5..3dfecb20d5e7 100644
--- a/drivers/pci/intel-iommu.c
+++ b/drivers/pci/intel-iommu.c
@@ -438,7 +438,8 @@ static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn)
                         continue;
 
                 for (i = 0; i < drhd->devices_cnt; i++)
-                        if (drhd->devices[i]->bus->number == bus &&
+                        if (drhd->devices[i] &&
+                            drhd->devices[i]->bus->number == bus &&
                             drhd->devices[i]->devfn == devfn)
                                 return drhd->iommu;