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nbd: fix uaf in nbd_open 

Commit 4af5f2e030 ("nbd: use blk_mq_alloc_disk and
blk_cleanup_disk") cleans up disk by blk_cleanup_disk() and it won't set
disk->private_data as NULL as before. UAF may be triggered in nbd_open()
if someone tries to open nbd device right after nbd_put() since nbd has
been free in nbd_dev_remove().

Fix this by implementing ->free_disk and free private data in it.

Fixes: 4af5f2e030 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk")
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20231107103435.2074904-1-lilingfeng@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Li Lingfeng 2023-11-07 18:34:35 +08:00 committed by Jens Axboe
parent d2f51b3516
commit 327462725b
1 changed files with 9 additions and 2 deletions
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11
drivers/block/nbd.c
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@ -250,7 +250,6 @@ static void nbd_dev_remove(struct nbd_device *nbd)
struct gendisk *disk = nbd->disk;
del_gendisk(disk);
put_disk(disk);
blk_mq_free_tag_set(&nbd->tag_set);
/*
@ -261,7 +260,7 @@ static void nbd_dev_remove(struct nbd_device *nbd)
idr_remove(&nbd_index_idr, nbd->index);
mutex_unlock(&nbd_index_mutex);
destroy_workqueue(nbd->recv_workq);
kfree(nbd);
put_disk(disk);
}
static void nbd_dev_remove_work(struct work_struct *work)
@ -1608,6 +1607,13 @@ static void nbd_release(struct gendisk *disk)
nbd_put(nbd);
}
static void nbd_free_disk(struct gendisk *disk)
{
struct nbd_device *nbd = disk->private_data;
kfree(nbd);
}
static const struct block_device_operations nbd_fops =
{
.owner = THIS_MODULE,
@ -1615,6 +1621,7 @@ static const struct block_device_operations nbd_fops =
.release = nbd_release,
.ioctl = nbd_ioctl,
.compat_ioctl = nbd_ioctl,
.free_disk = nbd_free_disk,
};
#if IS_ENABLED(CONFIG_DEBUG_FS)