Re: scsi: BUG in scsi_init_io

Christoph Hellwig
2017-02-19T17:25:53Z

On Sun, Feb 19, 2017 at 07:15:27AM +0000, Al Viro wrote:
> The root cause is unfixable without access to TARDIS and dose of
> antipsychotics sufficient to prevent /dev/sg API creation.
>
> What happens is that write to /dev/sg is given a request with non-zero
> ->iovec_count combined with zero ->dxfer_len. Or with ->dxferp pointing
> to an array full of empty iovecs.
>
> AFAICS, the minimal fix would be something like this:
>
> YAMissingSanityCheck in /dev/sg
>
> write permission to /dev/sg shouldn't be equivalent to the ability to trigger
> BUG_ON() while holding spinlocks...

Looks fine to me:

Reviewed-by: Christoph Hellwig <hch@lst.de>

The other thing we really need to consider is to finally merge the
SG_IO implementations for /dev/sg with the common block layer one.