1 files changed, 104 insertions, 81 deletions

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index dffbcc5c4ccf..8396a4f99526 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -226,24 +226,30 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
 	blk_mq_unfreeze_queue(lo->lo_queue);
 }
 
-static int
-figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
+/**
+ * loop_set_size() - sets device size and notifies userspace
+ * @lo: struct loop_device to set the size for
+ * @size: new size of the loop device
+ *
+ * Callers must validate that the size passed into this function fits into
+ * a sector_t, eg using loop_validate_size()
+ */
+static void loop_set_size(struct loop_device *lo, loff_t size)
 {
-	loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
-	sector_t x = (sector_t)size;
 	struct block_device *bdev = lo->lo_device;
 
-	if (unlikely((loff_t)x != size))
-		return -EFBIG;
-	if (lo->lo_offset != offset)
-		lo->lo_offset = offset;
-	if (lo->lo_sizelimit != sizelimit)
-		lo->lo_sizelimit = sizelimit;
-	set_capacity(lo->lo_disk, x);
-	bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
+	set_capacity(lo->lo_disk, size);
+	bd_set_size(bdev, size << SECTOR_SHIFT);
 	/* let user-space know about the new size */
 	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
-	return 0;
+}
+
+static void
+figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
+{
+	loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
+
+	loop_set_size(lo, size);
 }
 
 static inline int
@@ -1020,10 +1026,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	    !file->f_op->write_iter)
 		lo_flags |= LO_FLAGS_READ_ONLY;
 
-	error = -EFBIG;
 	size = get_loop_size(lo, file);
-	if ((loff_t)(sector_t)size != size)
-		goto out_unlock;
+
 	error = loop_prepare_queue(lo);
 	if (error)
 		goto out_unlock;
@@ -1057,11 +1061,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 
 	loop_update_rotational(lo);
 	loop_update_dio(lo);
-	set_capacity(lo->lo_disk, size);
-	bd_set_size(bdev, size << 9);
 	loop_sysfs_init(lo);
-	/* let user-space know about the new size */
-	kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+	loop_set_size(lo, size);
 
 	set_blocksize(bdev, S_ISBLK(inode->i_mode) ?
 		      block_size(inode->i_bdev) : PAGE_SIZE);
@@ -1275,82 +1276,50 @@ static int loop_clr_fd(struct loop_device *lo)
 	return __loop_clr_fd(lo, false);
 }
 
+/**
+ * loop_set_status_from_info - configure device from loop_info
+ * @lo: struct loop_device to configure
+ * @info: struct loop_info64 to configure the device with
+ *
+ * Configures the loop device parameters according to the passed
+ * in loop_info64 configuration.
+ */
 static int
-loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
+loop_set_status_from_info(struct loop_device *lo,
+			  const struct loop_info64 *info)
 {
 	int err;
 	struct loop_func_table *xfer;
 	kuid_t uid = current_uid();
-	struct block_device *bdev;
-	bool partscan = false;
 
-	err = mutex_lock_killable(&loop_ctl_mutex);
-	if (err)
-		return err;
-	if (lo->lo_encrypt_key_size &&
-	    !uid_eq(lo->lo_key_owner, uid) &&
-	    !capable(CAP_SYS_ADMIN)) {
-		err = -EPERM;
-		goto out_unlock;
-	}
-	if (lo->lo_state != Lo_bound) {
-		err = -ENXIO;
-		goto out_unlock;
-	}
-	if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) {
-		err = -EINVAL;
-		goto out_unlock;
-	}
-
-	if (lo->lo_offset != info->lo_offset ||
-	    lo->lo_sizelimit != info->lo_sizelimit) {
-		sync_blockdev(lo->lo_device);
-		invalidate_bdev(lo->lo_device);
-	}
-
-	/* I/O need to be drained during transfer transition */
-	blk_mq_freeze_queue(lo->lo_queue);
+	if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
+		return -EINVAL;
 
 	err = loop_release_xfer(lo);
 	if (err)
-		goto out_unfreeze;
+		return err;
 
 	if (info->lo_encrypt_type) {
 		unsigned int type = info->lo_encrypt_type;
 
-		if (type >= MAX_LO_CRYPT) {
-			err = -EINVAL;
-			goto out_unfreeze;
-		}
+		if (type >= MAX_LO_CRYPT)
+			return -EINVAL;
 		xfer = xfer_funcs[type];
-		if (xfer == NULL) {
-			err = -EINVAL;
-			goto out_unfreeze;
-		}
+		if (xfer == NULL)
+			return -EINVAL;
 	} else
 		xfer = NULL;
 
 	err = loop_init_xfer(lo, xfer, info);
 	if (err)
-		goto out_unfreeze;
+		return err;
 
-	if (lo->lo_offset != info->lo_offset ||
-	    lo->lo_sizelimit != info->lo_sizelimit) {
-		/* kill_bdev should have truncated all the pages */
-		if (lo->lo_device->bd_inode->i_mapping->nrpages) {
-			err = -EAGAIN;
-			pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
-				__func__, lo->lo_number, lo->lo_file_name,
-				lo->lo_device->bd_inode->i_mapping->nrpages);
-			goto out_unfreeze;
-		}
-		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) {
-			err = -EFBIG;
-			goto out_unfreeze;
-		}
-	}
+	/* Avoid assigning overflow values */
+	if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
+		return -EOVERFLOW;
 
-	loop_config_discard(lo);
+	lo->lo_offset = info->lo_offset;
+	lo->lo_sizelimit = info->lo_sizelimit;
 
 	memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
 	memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
@@ -1375,6 +1344,63 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 		lo->lo_key_owner = uid;
 	}
 
+	return 0;
+}
+
+static int
+loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
+{
+	int err;
+	struct block_device *bdev;
+	kuid_t uid = current_uid();
+	bool partscan = false;
+	bool size_changed = false;
+
+	err = mutex_lock_killable(&loop_ctl_mutex);
+	if (err)
+		return err;
+	if (lo->lo_encrypt_key_size &&
+	    !uid_eq(lo->lo_key_owner, uid) &&
+	    !capable(CAP_SYS_ADMIN)) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+	if (lo->lo_state != Lo_bound) {
+		err = -ENXIO;
+		goto out_unlock;
+	}
+
+	if (lo->lo_offset != info->lo_offset ||
+	    lo->lo_sizelimit != info->lo_sizelimit) {
+		size_changed = true;
+		sync_blockdev(lo->lo_device);
+		invalidate_bdev(lo->lo_device);
+	}
+
+	/* I/O need to be drained during transfer transition */
+	blk_mq_freeze_queue(lo->lo_queue);
+
+	if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) {
+		/* If any pages were dirtied after invalidate_bdev(), try again */
+		err = -EAGAIN;
+		pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
+			__func__, lo->lo_number, lo->lo_file_name,
+			lo->lo_device->bd_inode->i_mapping->nrpages);
+		goto out_unfreeze;
+	}
+
+	err = loop_set_status_from_info(lo, info);
+	if (err)
+		goto out_unfreeze;
+
+	if (size_changed) {
+		loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
+					   lo->lo_backing_file);
+		loop_set_size(lo, new_size);
+	}
+
+	loop_config_discard(lo);
+
 	/* update dio if lo_offset or transfer is changed */
 	__loop_update_dio(lo, lo->use_dio);
 
@@ -1415,11 +1441,6 @@ loop_get_status(struct loop_device *lo, struct loop_info64 *info)
 	info->lo_number = lo->lo_number;
 	info->lo_offset = lo->lo_offset;
 	info->lo_sizelimit = lo->lo_sizelimit;
-
-	/* loff_t vars have been assigned __u64 */
-	if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
-		return -EOVERFLOW;
-
 	info->lo_flags = lo->lo_flags;
 	memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
 	memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
@@ -1555,7 +1576,9 @@ static int loop_set_capacity(struct loop_device *lo)
 	if (unlikely(lo->lo_state != Lo_bound))
 		return -ENXIO;
 
-	return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
+	figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
+
+	return 0;
 }
 
 static int loop_set_dio(struct loop_device *lo, unsigned long arg)