iommu: Don't overwrite domain pointer when there is no default_domain
IOMMU drivers that do not support default domains, but make
use of the the group->domain pointer can get that pointer
overwritten with NULL on device add/remove.
Make sure this can't happen by only overwriting the domain
pointer when it is NULL.
Cc: stable@vger.kernel.org # v4.4+
Fixes: 1228236de5f9 ('iommu: Move default domain allocation to iommu_group_get_for_dev()')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index bfd4f7c..b9df141 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -848,7 +848,8 @@
if (!group->default_domain) {
group->default_domain = __iommu_domain_alloc(dev->bus,
IOMMU_DOMAIN_DMA);
- group->domain = group->default_domain;
+ if (!group->domain)
+ group->domain = group->default_domain;
}
ret = iommu_group_add_device(group, dev);