Re: [PATCH] nbd: fix uaf in nbd_open

[Li Lingfeng]

在 2023/11/3 16:12, Christoph Hellwig 写道:
> On Fri, Nov 03, 2023 at 06:13:34PM +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 refcount
> > of nbd device is zero and private_data is not NULL.
> I don't think this is the right fix.  nbd needs to move to ->free_disk
> to free it's private data.
Thanks for your advice, I will send v2 soon.