Re: [PATCH] ata: libata-scsi: fix ata_scsi_security_inout_xlat() buffer length conversion

[Niklas Cassel <cassel@kernel.org>]

On Wed, Jun 24, 2026 at 01:51:14PM +0200, Niklas Cassel wrote:
> So if this is not the case, I think the fix should be in SCSI.
> I guess we could add code in libata to return an error if INC_512 set to zero,
> and scsi_bufflen(scmd) (+ scmd->extra_len ?) is not a multiple of 512.
> But to me, for SECURITY PROTOCOL OUT, the current libata code looks correct.

s/scsi_bufflen()/TRANSFER LENGTH (cdb[6:9])/


> For your workaround, we should probably ensure that it is only applied for
> SECURITY PROTOCOL IN (rx). But... would we not be violating the SAT spec?
> 
> If we get a SCSI command with a scsi_bufflen that is not 512 aligned, and we
> apply your workaround, we will transfer less than scsi_bufflen to the device
> (since you now round down instead of up), but AFAICT, when calling
> ata_scsi_qc_complete() + ata_scsi_qc_done(), nowhere do I see that we call
> scsi_set_resid(), to indicate that the transfer has been truncated (i.e.
> that we did not transfer all scsi_bufflen() number of bytes), so it seems to
> me that your workaround would silently truncate the transfer, without informing
> the upper layer (SCSI) that the result is truncated.

s/scsi_bufflen()/ALLOCATION LENGTH (cdb[6:9])/


Kind regards,
Niklas