iommu/arm-smmu: fix null-pointer dereference in arm_smmu_add_device

Commit c54451a "iommu/arm-smmu: Fix the error path in arm_smmu_add_device"
removed fwspec assignment in legacy_binding path as redundant which is
wrong. It needs to be updated after fwspec initialisation in
arm_smmu_register_legacy_master() as it is dereferenced later. Without
this there is a NULL-pointer dereference panic during boot on some hosts.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index b97188acc4f1006185a5f8cb4fb3ee0e5cf735cf..2d80fa8a0634aba34b366609d8bcc50f432bb31c 100644 (file)
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1519,6 +1519,13 @@ static int arm_smmu_add_device(struct device *dev)
 
        if (using_legacy_binding) {
                ret = arm_smmu_register_legacy_master(dev, &smmu);
+
+               /*
+                * If dev->iommu_fwspec is initally NULL, arm_smmu_register_legacy_master()
+                * will allocate/initialise a new one. Thus we need to update fwspec for
+                * later use.
+                */
+               fwspec = dev->iommu_fwspec;
                if (ret)
                        goto out_free;
        } else if (fwspec && fwspec->ops == &arm_smmu_ops) {