diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index 54cf4d8..4369923 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -495,7 +495,11 @@ int iopt_map_file_pages(struct iommufd_ctx *ictx, struct io_pagetable *iopt,
 		return -EOVERFLOW;
 
 	start_byte = start - ALIGN_DOWN(start, PAGE_SIZE);
-	dmabuf = dma_buf_get(fd);
+	if (IS_ENABLED(CONFIG_DMA_SHARED_BUFFER))
+		dmabuf = dma_buf_get(fd);
+	else
+		dmabuf = ERR_PTR(-ENXIO);
+
 	if (!IS_ERR(dmabuf)) {
 		pages = iopt_alloc_dmabuf_pages(ictx, dmabuf, start_byte, start,
 						length,
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index c4322fd..550ff36 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -1184,14 +1184,20 @@ static int iommufd_test_add_reserved(struct iommufd_ucmd *ucmd,
 				     unsigned int mockpt_id,
 				     unsigned long start, size_t length)
 {
+	unsigned long last;
 	struct iommufd_ioas *ioas;
 	int rc;
 
+	if (!length)
+		return -EINVAL;
+	if (check_add_overflow(start, length - 1, &last))
+		return -EOVERFLOW;
+
 	ioas = iommufd_get_ioas(ucmd->ictx, mockpt_id);
 	if (IS_ERR(ioas))
 		return PTR_ERR(ioas);
 	down_write(&ioas->iopt.iova_rwsem);
-	rc = iopt_reserve_iova(&ioas->iopt, start, start + length - 1, NULL);
+	rc = iopt_reserve_iova(&ioas->iopt, start, last, NULL);
 	up_write(&ioas->iopt.iova_rwsem);
 	iommufd_put_object(ucmd->ictx, &ioas->obj);
 	return rc;
@@ -1215,8 +1221,10 @@ static int iommufd_test_md_check_pa(struct iommufd_ucmd *ucmd,
 	page_size = 1 << __ffs(mock->domain.pgsize_bitmap);
 	if (iova % page_size || length % page_size ||
 	    (uintptr_t)uptr % page_size ||
-	    check_add_overflow((uintptr_t)uptr, (uintptr_t)length, &end))
-		return -EINVAL;
+	    check_add_overflow((uintptr_t)uptr, (uintptr_t)length, &end)) {
+		rc = -EINVAL;
+		goto out_put;
+	}
 
 	for (; length; length -= page_size) {
 		struct page *pages[1];
diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c
index 10e051b..dadad27 100644
--- a/tools/testing/selftests/iommu/iommufd.c
+++ b/tools/testing/selftests/iommu/iommufd.c
@@ -755,9 +755,6 @@ TEST_F(iommufd_ioas, get_hw_info)
 		struct iommu_test_hw_info info;
 		uint64_t trailing_bytes;
 	} buffer_larger;
-	struct iommu_test_hw_info_buffer_smaller {
-		__u32 flags;
-	} buffer_smaller;
 
 	if (self->device_id) {
 		uint8_t max_pasid = 0;
@@ -789,8 +786,9 @@ TEST_F(iommufd_ioas, get_hw_info)
 		 * the fields within the size range still gets updated.
 		 */
 		test_cmd_get_hw_info(self->device_id,
-				     IOMMU_HW_INFO_TYPE_DEFAULT,
-				     &buffer_smaller, sizeof(buffer_smaller));
+				     IOMMU_HW_INFO_TYPE_DEFAULT, &buffer_exact,
+				     offsetofend(struct iommu_test_hw_info,
+						 flags));
 		test_cmd_get_hw_info_pasid(self->device_id, &max_pasid);
 		ASSERT_EQ(0, max_pasid);
 		if (variant->pasid_capable) {