linux-kernel - Re: "Fix ATAPI transfer lengths" causes CD writing regression

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <472872F6.70802@garzik.org>
Date:	Wed, 31 Oct 2007 08:20:06 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Jens Axboe <jens.axboe@...cle.com>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>, Daniel Drake <dsd@...too.org>,
	linux list <linux-kernel@...r.kernel.org>,
	linux-ide@...r.kernel.org
Subject: Re: "Fix ATAPI transfer lengths" causes CD writing regression

Jens Axboe wrote:
> On Wed, Oct 31 2007, Alan Cox wrote:
>> On Tue, 30 Oct 2007 19:21:29 +0000
>> Daniel Drake <dsd@...too.org> wrote:
>>
>>> Alan Cox wrote:
>>>> I would guess Brasero is issuing a command with the length of data
>>>> wrongly set. In the old code that might well just produce errors of the
>>>> "Umm wtf is this data left over for ?", with the new code the drive is
>>>> likely to change state as it knows the transfer size and that will
>>>> *correctly* cause an HSM error and what follows.
>>>>
>>>> Now the question is who gets the length wrong - Brasero or the ata
>>>> translation code in libata
>>> Brasero does exactly the same as my test app which I attached to my last 
>>> mail. Is my test app wrong?
>> Would need to double check the SCSI specificatons to be sure but I think
>> you are asking for less data than the drive wishes to provide. You
>> aren't allowed to do that with ATA.
> 
> ide-cd handles this by throwing the excess away, which I think is the
> sane way to do this.

That's easy for the PIO case.  But CD writing is normally DMA, which 
means you will get a DMA engine exception if the device wants to give 
you more data than the scatter/gather entries permit.

	Jeff



-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/