iommu: Check the result of iommu_group_get() for NULL

The result of iommu_group_get() was being blindly used in both
attach and detach which results in a dereference when trying
to work with an unknown device.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3de5c0bcb5cc9f32b6fb615ce38f5729ae86d407..69fef991c651de26c60e5c3cb5f2e6be0c0d0fcb 100644 (file)
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1303,6 +1303,9 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
        int ret;
 
        group = iommu_group_get(dev);
+       if (!group)
+               return -ENODEV;
+
        /*
         * Lock the group to make sure the device-count doesn't
         * change while we are attaching
@@ -1341,6 +1344,8 @@ void iommu_detach_device(struct iommu_domain *domain, struct device *dev)
        struct iommu_group *group;
 
        group = iommu_group_get(dev);
+       if (!group)
+               return;
 
        mutex_lock(&group->mutex);
        if (iommu_group_device_count(group) != 1) {