iommu/arm-smmu-v3: Don't free page table ops twice

commit 57d72e15 upstream.

Kasan reports a double free when finalise_stage_fn fails: the io_pgtable
ops are freed by arm_smmu_domain_finalise and then again by
arm_smmu_domain_free. Prevent this by leaving pgtbl_ops empty on failure.

Fixes: 48ec83bc ("iommu/arm-smmu: Add initial driver support for ARM SMMUv3 devices")
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/iommu/arm-smmu-v3.c

@@ -1541,13 +1541,15 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain)
 		return -ENOMEM;
 
 	arm_smmu_ops.pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
-	smmu_domain->pgtbl_ops = pgtbl_ops;
 
 	ret = finalise_stage_fn(smmu_domain, &pgtbl_cfg);
-	if (IS_ERR_VALUE(ret))
+	if (IS_ERR_VALUE(ret)) {
 		free_io_pgtable_ops(pgtbl_ops);
-
 		return ret;
+	}
+
+	smmu_domain->pgtbl_ops = pgtbl_ops;
+	return 0;
 }
 
 static struct arm_smmu_group *arm_smmu_group_get(struct device *dev)