Re: [PATCH v2] nbd: fix uaf in nbd_open

[Josef Bacik]

On Tue, Nov 07, 2023 at 06:34:35PM +0800, Li Lingfeng wrote:
> From: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
> 
> Commit 4af5f2e03013 ("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: 4af5f2e03013 ("nbd: use blk_mq_alloc_disk and blk_cleanup_disk")
> Signed-off-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>

Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>

Thanks,

Josef