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

Pull iommufd fixes from Jason Gunthorpe:
 "Four syzkaller found bugs:

   - Corruption during error unwind in iommufd_access_change_ioas()

   - Overlapping IDs in the test suite due to out of order destruction

   - Missing locking for access->ioas in the test suite

   - False failures in the test suite validation logic with huge pages"

* tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd:
  iommufd/selftest: Don't check map/unmap pairing with HUGE_PAGES
  iommufd: Fix protection fault in iommufd_test_syz_conv_iova
  iommufd/selftest: Fix mock_dev_num bug
  iommufd: Fix iopt_access_list_id overwrite bug

drivers/iommu/iommufd/io_pagetable.c

@@ -1330,20 +1330,23 @@ int iopt_disable_large_pages(struct io_pagetable *iopt)
 
 int iopt_add_access(struct io_pagetable *iopt, struct iommufd_access *access)
 {
+	u32 new_id;
 	int rc;
 
 	down_write(&iopt->domains_rwsem);
 	down_write(&iopt->iova_rwsem);
-	rc = xa_alloc(&iopt->access_list, &access->iopt_access_list_id, access,
-		      xa_limit_16b, GFP_KERNEL_ACCOUNT);
+	rc = xa_alloc(&iopt->access_list, &new_id, access, xa_limit_16b,
+		      GFP_KERNEL_ACCOUNT);
+
 	if (rc)
 		goto out_unlock;
 
 	rc = iopt_calculate_iova_alignment(iopt);
 	if (rc) {
-		xa_erase(&iopt->access_list, access->iopt_access_list_id);
+		xa_erase(&iopt->access_list, new_id);
 		goto out_unlock;
 	}
+	access->iopt_access_list_id = new_id;
 
 out_unlock:
 	up_write(&iopt->iova_rwsem);

drivers/iommu/iommufd/selftest.c

@@ -36,7 +36,7 @@ static struct mock_bus_type iommufd_mock_bus_type = {
 	},
 };
 
-static atomic_t mock_dev_num;
+static DEFINE_IDA(mock_dev_ida);
 
 enum {
 	MOCK_DIRTY_TRACK = 1,
@@ -63,7 +63,7 @@ enum {
  * In syzkaller mode the 64 bit IOVA is converted into an nth area and offset
  * value. This has a much smaller randomization space and syzkaller can hit it.
  */
-static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
+static unsigned long __iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
 						  u64 *iova)
 {
 	struct syz_layout {
@@ -88,6 +88,21 @@ static unsigned long iommufd_test_syz_conv_iova(struct io_pagetable *iopt,
 	return 0;
 }
 
+static unsigned long iommufd_test_syz_conv_iova(struct iommufd_access *access,
+						u64 *iova)
+{
+	unsigned long ret;
+
+	mutex_lock(&access->ioas_lock);
+	if (!access->ioas) {
+		mutex_unlock(&access->ioas_lock);
+		return 0;
+	}
+	ret = __iommufd_test_syz_conv_iova(&access->ioas->iopt, iova);
+	mutex_unlock(&access->ioas_lock);
+	return ret;
+}
+
 void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd,
 				   unsigned int ioas_id, u64 *iova, u32 *flags)
 {
@@ -100,7 +115,7 @@ void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd,
 	ioas = iommufd_get_ioas(ucmd->ictx, ioas_id);
 	if (IS_ERR(ioas))
 		return;
-	*iova = iommufd_test_syz_conv_iova(&ioas->iopt, iova);
+	*iova = __iommufd_test_syz_conv_iova(&ioas->iopt, iova);
 	iommufd_put_object(ucmd->ictx, &ioas->obj);
 }
 
@@ -123,6 +138,7 @@ enum selftest_obj_type {
 struct mock_dev {
 	struct device dev;
 	unsigned long flags;
+	int id;
 };
 
 struct selftest_obj {
@@ -430,20 +446,27 @@ static size_t mock_domain_unmap_pages(struct iommu_domain *domain,
 
 			/*
 			 * iommufd generates unmaps that must be a strict
-			 * superset of the map's performend So every starting
-			 * IOVA should have been an iova passed to map, and the
+			 * superset of the map's performend So every
+			 * starting/ending IOVA should have been an iova passed
+			 * to map.
 			 *
-			 * First IOVA must be present and have been a first IOVA
-			 * passed to map_pages
+			 * This simple logic doesn't work when the HUGE_PAGE is
+			 * turned on since the core code will automatically
+			 * switch between the two page sizes creating a break in
+			 * the unmap calls. The break can land in the middle of
+			 * contiguous IOVA.
 			 */
+			if (!(domain->pgsize_bitmap & MOCK_HUGE_PAGE_SIZE)) {
 				if (first) {
 					WARN_ON(ent && !(xa_to_value(ent) &
 							 MOCK_PFN_START_IOVA));
 					first = false;
 				}
-			if (pgcount == 1 && cur + MOCK_IO_PAGE_SIZE == pgsize)
+				if (pgcount == 1 &&
+				    cur + MOCK_IO_PAGE_SIZE == pgsize)
 					WARN_ON(ent && !(xa_to_value(ent) &
 							 MOCK_PFN_LAST_IOVA));
+			}
 
 			iova += MOCK_IO_PAGE_SIZE;
 			ret += MOCK_IO_PAGE_SIZE;
@@ -631,7 +654,7 @@ static void mock_dev_release(struct device *dev)
 {
 	struct mock_dev *mdev = container_of(dev, struct mock_dev, dev);
 
-	atomic_dec(&mock_dev_num);
+	ida_free(&mock_dev_ida, mdev->id);
 	kfree(mdev);
 }
 
@@ -653,8 +676,12 @@ static struct mock_dev *mock_dev_create(unsigned long dev_flags)
 	mdev->dev.release = mock_dev_release;
 	mdev->dev.bus = &iommufd_mock_bus_type.bus;
 
-	rc = dev_set_name(&mdev->dev, "iommufd_mock%u",
-			  atomic_inc_return(&mock_dev_num));
+	rc = ida_alloc(&mock_dev_ida, GFP_KERNEL);
+	if (rc < 0)
+		goto err_put;
+	mdev->id = rc;
+
+	rc = dev_set_name(&mdev->dev, "iommufd_mock%u", mdev->id);
 	if (rc)
 		goto err_put;
 
@@ -1156,7 +1183,7 @@ static int iommufd_test_access_pages(struct iommufd_ucmd *ucmd,
 	}
 
 	if (flags & MOCK_FLAGS_ACCESS_SYZ)
-		iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt,
+		iova = iommufd_test_syz_conv_iova(staccess->access,
 					&cmd->access_pages.iova);
 
 	npages = (ALIGN(iova + length, PAGE_SIZE) -
@@ -1258,7 +1285,7 @@ static int iommufd_test_access_rw(struct iommufd_ucmd *ucmd,
 	}
 
 	if (flags & MOCK_FLAGS_ACCESS_SYZ)
-		iova = iommufd_test_syz_conv_iova(&staccess->access->ioas->iopt,
+		iova = iommufd_test_syz_conv_iova(staccess->access,
 				&cmd->access_rw.iova);
 
 	rc = iommufd_access_rw(staccess->access, iova, tmp, length, flags);