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From: Douglas Gilbert <dgilbert@interlog.com>
To: linux-scsi <linux-scsi@vger.kernel.org>,
	linux-ide@vger.kernel.org,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Hannes Reinecke <hare@suse.de>,
	Tony Asleson <tasleson@redhat.com>
Subject: libata: big endian bug in VPD page 89 (ATA Information)
Date: Sun, 13 Jun 2021 21:28:03 -0400	[thread overview]
Message-ID: <f0d1073e-b4a0-c255-41a3-ff52f1553c0f@interlog.com> (raw)

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.

Doug Gilbert

             reply	other threads:[~2021-06-14  1:28 UTC|newest]

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

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