Re: [syzbot] KASAN: use-after-free Read in nbd_genl_connect (2)

[Christoph Hellwig]

On Wed, Aug 25, 2021 at 04:55:25PM +0800, Hillf Danton wrote:
> Because no nbd is kfreed without being removed from the nbd idr, finding
> a freed nbd in the idr with nbd_index_mutex held means the nbd is not a
> valid pointer, and fix the uaf by cutting the chance for invalid nbd.
> 
> Only for thoughts now.

That is a bug, but not really the problem here.  I think the issue
is the completion issue that Tetsuo reported.  Looking into that at
the moment.