diff options
| author | Yu Kuai <yukuai3@huawei.com> | 2022-11-15 22:10:52 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-11-16 15:19:56 -0700 |
| commit | 62f535e1f061b4c2cc76061b6b59af9f9335ee34 (patch) | |
| tree | 32c2a4bf133cd6831d6226656969d6eefbe16c11 /block/holder.c | |
| parent | 7abc077788363ac7194aefd355306f8e974feff7 (diff) | |
block: fix use after free for bd_holder_dir
Currently, the caller of bd_link_disk_holer() get 'bdev' by
blkdev_get_by_dev(), which will look up 'bdev' by inode number 'dev'.
Howerver, it's possible that del_gendisk() can be called currently, and
'bd_holder_dir' can be freed before bd_link_disk_holer() access it, thus
use after free is triggered.
t1: t2:
bdev = blkdev_get_by_dev
del_gendisk
kobject_put(bd_holder_dir)
kobject_free()
bd_link_disk_holder
Fix the problem by checking disk is still live and grabbing a reference
to 'bd_holder_dir' first in bd_link_disk_holder().
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221115141054.1051801-9-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/holder.c')
| -rw-r--r-- | block/holder.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/block/holder.c b/block/holder.c index dd9327b43ce0..c8e462053f49 100644 --- a/block/holder.c +++ b/block/holder.c @@ -65,12 +65,24 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) if (WARN_ON_ONCE(!disk->slave_dir)) return -EINVAL; - mutex_lock(&disk->open_mutex); + /* + * del_gendisk drops the initial reference to bd_holder_dir, so we + * need to keep our own here to allow for cleanup past that point. + */ + mutex_lock(&bdev->bd_disk->open_mutex); + if (!disk_live(bdev->bd_disk)) { + mutex_unlock(&bdev->bd_disk->open_mutex); + return -ENODEV; + } + kobject_get(bdev->bd_holder_dir); + mutex_unlock(&bdev->bd_disk->open_mutex); + mutex_lock(&disk->open_mutex); WARN_ON_ONCE(!bdev->bd_holder); holder = bd_find_holder_disk(bdev, disk); if (holder) { + kobject_put(bdev->bd_holder_dir); holder->refcnt++; goto out_unlock; } @@ -92,11 +104,6 @@ int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) goto out_del_symlink; list_add(&holder->list, &disk->slave_bdevs); - /* - * del_gendisk drops the initial reference to bd_holder_dir, so we need - * to keep our own here to allow for cleanup past that point. - */ - kobject_get(bdev->bd_holder_dir); mutex_unlock(&disk->open_mutex); return 0; @@ -106,6 +113,8 @@ out_free_holder: kfree(holder); out_unlock: mutex_unlock(&disk->open_mutex); + if (ret) + kobject_put(bdev->bd_holder_dir); return ret; } EXPORT_SYMBOL_GPL(bd_link_disk_holder); |