Merge tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd

Pull iommufd fixes from Jason Gunthorpe:

 - An invalid VA range can be be put in a pages and eventually trigger
   WARN_ON, reject it early

 - Use of the wrong start index value when doing the complex batch carry
   scheme

 - Wrong store ordering resulting in corrupting data used in a later
   calculation that corrupted the batch structure during carry

* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd:
  iommufd: Do not corrupt the pfn list when doing batch carry
  iommufd: Fix unpinning of pages when an access is present
  iommufd: Check for uptr overflow

Author: torvalds

drivers/iommu/iommufd/pages.c

@@ -294,9 +294,9 @@ static void batch_clear_carry(struct pfn_batch *batch, unsigned int keep_pfns)
 			batch->npfns[batch->end - 1] < keep_pfns);
 
 	batch->total_pfns = keep_pfns;
-	batch->npfns[0] = keep_pfns;
 	batch->pfns[0] = batch->pfns[batch->end - 1] +
 			 (batch->npfns[batch->end - 1] - keep_pfns);
+	batch->npfns[0] = keep_pfns;
 	batch->end = 0;
 }
 
@@ -1142,6 +1142,7 @@ struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length,
 				    bool writable)
 {
 	struct iopt_pages *pages;
+	unsigned long end;
 
 	/*
 	 * The iommu API uses size_t as the length, and protect the DIV_ROUND_UP
@@ -1150,6 +1151,9 @@ struct iopt_pages *iopt_alloc_pages(void __user *uptr, unsigned long length,
 	if (length > SIZE_MAX - PAGE_SIZE || length == 0)
 		return ERR_PTR(-EINVAL);
 
+	if (check_add_overflow((unsigned long)uptr, length, &end))
+		return ERR_PTR(-EOVERFLOW);
+
 	pages = kzalloc(sizeof(*pages), GFP_KERNEL_ACCOUNT);
 	if (!pages)
 		return ERR_PTR(-ENOMEM);
@@ -1203,13 +1207,21 @@ iopt_area_unpin_domain(struct pfn_batch *batch, struct iopt_area *area,
 			unsigned long start =
 				max(start_index, *unmapped_end_index);
 
+			if (IS_ENABLED(CONFIG_IOMMUFD_TEST) &&
+			    batch->total_pfns)
+				WARN_ON(*unmapped_end_index -
+						batch->total_pfns !=
+					start_index);
 			batch_from_domain(batch, domain, area, start,
 					  last_index);
-			batch_last_index = start + batch->total_pfns - 1;
+			batch_last_index = start_index + batch->total_pfns - 1;
 		} else {
 			batch_last_index = last_index;
 		}
 
+		if (IS_ENABLED(CONFIG_IOMMUFD_TEST))
+			WARN_ON(batch_last_index > real_last_index);
+
 		/*
 		 * unmaps must always 'cut' at a place where the pfns are not
 		 * contiguous to pair with the maps that always install