archive mirror
 help / color / mirror / Atom feed
From: Hannes Reinecke <>
To:, linux-scsi <>,,
	"Martin K. Petersen" <>,
	Tony Asleson <>
Subject: Re: libata: big endian bug in VPD page 89 (ATA Information)
Date: Mon, 14 Jun 2021 08:00:00 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 6/14/21 3:28 AM, Douglas Gilbert wrote:
> In drivers/ata/libata-scsi.c in function ata_scsiop_inq_89() there is
> this line, just before the return:
>        memcpy(&rbuf[60], &args->id[0], 512);
> args->id[0] is the first u16 word of an array from the ATA IDENTIFY
> DEVICE response while rbuf is an array of u8 that will become the
> response to a SCSI INQUIRY(VPD=89h). Given the definition of VPD
> page 89h:
>    byte 60+0:  ATA IDENTIFY DEVICE data word 0 bits 7:0
>    byte 60+1:  ATA IDENTIFY DEVICE data word 0 bits 15:8
>    byte 60+2:  ATA IDENTIFY DEVICE data word 1 bits 7:0
>    ........
> then that memcpy is just fine and dandy on a little endian machine.
> On a big endian machine, not so much.
> Would this call after the memcpy fix things?
>     swap_buf_le16((u16 *)(rbuf + 60), ATA_ID_WORDS);
> That function (in libata-core.c) only swaps bytes in 16 bit words
> on big endian machines.
It might. But probably no-one ever ran libata code on big-endian machines.
They are becoming rare these days; I wouldn't know where to look.
So if you had a chance to run it please give it a go.
Truth to be told, I won't be surprised if there would be more issues 
lurking in the libata code.


Dr. Hannes Reinecke                Kernel Storage Architect                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

      reply	other threads:[~2021-06-14  6:00 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14  1:28 Douglas Gilbert
2021-06-14  6:00 ` Hannes Reinecke [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \
    --subject='Re: libata: big endian bug in VPD page 89 (ATA Information)' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).