diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index fe789c2dc0c9..623cc608ca0c 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -489,6 +489,9 @@ int iommufd_hwpt_get_dirty_bitmap(struct iommufd_ucmd *ucmd)
 	return rc;
 }
 
+/* An arbitrary entry_num cap, far above any realistic invalidation batch */
+#define IOMMU_HWPT_INVALIDATE_ENTRY_NUM_MAX (1U << 19)
+
 int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
 {
 	struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
@@ -507,7 +510,13 @@ int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
 		goto out;
 	}
 
-	if (cmd->entry_num && (!cmd->data_uptr || !cmd->entry_len)) {
+	/*
+	 * Bound entry_num and entry_len so a single call cannot pin the CPU;
+	 * entry_len also caps the copy_struct_from_user() trailing-zero scan.
+	 */
+	if (cmd->entry_num &&
+	    (!cmd->data_uptr || !cmd->entry_len || cmd->entry_len > PAGE_SIZE ||
+	     cmd->entry_num > IOMMU_HWPT_INVALIDATE_ENTRY_NUM_MAX)) {
 		rc = -EINVAL;
 		goto out;
 	}