block: check disk exist before trying to add partition

If disk have been deleted, we should return fail for ioctl BLKPG_DEL_PARTITION. Otherwise, the directory /sys/class/block may remain invalid symlinks file. The race as following: blkdev_open del_gendisk disk->flags &= ~GENHD_FL_UP; blk_drop_partitions blkpg_ioctl bdev_add_partition add_partition device_add device_add_class_symlinks ioctl may add_partition after del_gendisk() have tried to delete partitions. Then, symlinks file will be created. Reviewed-by: Jan Kara <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Yufen Yu <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Jens Axboe <[email protected]>
niw · Jul 1, 2021 · b5cfbd3 · b5cfbd3
1 parent efee99e
commit b5cfbd3
Showing 1 changed file with 16 additions and 7 deletions.
diff --git a/block/partitions/core.c b/block/partitions/core.c
@@ -453,17 +453,26 @@ int bdev_add_partition(struct block_device *bdev, int partno,
 		sector_t start, sector_t length)
 {
 	struct block_device *part;
+	struct gendisk *disk = bdev->bd_disk;
+	int ret;
 
-	mutex_lock(&bdev->bd_disk->open_mutex);
-	if (partition_overlaps(bdev->bd_disk, start, length, -1)) {
-		mutex_unlock(&bdev->bd_disk->open_mutex);
-		return -EBUSY;
+	mutex_lock(&disk->open_mutex);
+	if (!(disk->flags & GENHD_FL_UP)) {
+		ret = -ENXIO;
+		goto out;
 	}
 
-	part = add_partition(bdev->bd_disk, partno, start, length,
+	if (partition_overlaps(disk, start, length, -1)) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	part = add_partition(disk, partno, start, length,
 			ADDPART_FLAG_NONE, NULL);
-	mutex_unlock(&bdev->bd_disk->open_mutex);
-	return PTR_ERR_OR_ZERO(part);
+	ret = PTR_ERR_OR_ZERO(part);
+out:
+	mutex_unlock(&disk->open_mutex);
+	return ret;
 }
 
 int bdev_del_partition(struct block_device *bdev, int partno)