Re: [PATCH] nbd: freeze the queue while we're adding connections

[Jens Axboe <axboe@kernel.dk>]

On 1/25/21 10:21 AM, Josef Bacik wrote:
> When setting up a device, we can krealloc the config->socks array to add
> new sockets to the configuration.  However if we happen to get a IO
> request in at this point even though we aren't setup we could hit a UAF,
> as we deref config->socks without any locking, assuming that the
> configuration was setup already and that ->socks is safe to access it as
> we have a reference on the configuration.
> 
> But there's nothing really preventing IO from occurring at this point of
> the device setup, we don't want to incur the overhead of a lock to
> access ->socks when it will never change while the device is running.
> To fix this UAF scenario simply freeze the queue if we are adding
> sockets.  This will protect us from this particular case without adding
> any additional overhead for the normal running case.

Applied, thanks.

-- 
Jens Axboe