Re: [patch 34/37] libata bugfix: HDIO_DRIVE_TASK

[Mark Lord <mlord@pobox.com>]

Greg KH wrote:
> -stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> From: Mark Lord <liml@rtr.ca>
> 
> libata bugfix: HDIO_DRIVE_TASK
> 
> I was trying to use HDIO_DRIVE_TASK for something today,
> and discovered that the libata implementation does not copy
> over the upper four LBA bits from args[6].
> 
> This is serious, as any tools using this ioctl would have their
> commands applied to the wrong sectors on the drive, possibly resulting
> in disk corruption.
> 
> Ideally, newer apps should use SG_IO/ATA_16 directly,
> avoiding this bug.  But with libata poised to displace drivers/ide,
> better compatibility here is a must.
> 
> This patch fixes libata to use the upper four LBA bits passed
> in from the ioctl.
> 
> The original drivers/ide implementation copies over all bits
> except for the master/slave select bit.  With this patch,
> libata will copy only the four high-order LBA bits,
> just in case there are assumptions elsewhere in libata (?).
> 
> Signed-off-by: Mark Lord <mlord@pobox.com>
> Cc: Chuck Ebbert <cebbert@redhat.com>
> Signed-off-by: Jeff Garzik <jeff@garzik.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
..

Mmmm.. I've just noticed another bit we should  be preserving there,
both for *stable* and current mainline.

Instead of:

> +	scsi_cmd[13] = args[6] & 0x0f;

We should be doing:

> +	scsi_cmd[13] = args[6] & 0x4f;

As-is, the patch still helps, but it is not as useful as it could be.
Here's the fixed version.  I'm also sending out a 2.6.21 patch via Jeff.

Signed-off-by: Mark Lord <mlord@pobox.com>
---
 drivers/ata/libata-scsi.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -295,6 +295,7 @@ int ata_task_ioctl(struct scsi_device *s
 	scsi_cmd[8]  = args[3];
 	scsi_cmd[10] = args[4];
 	scsi_cmd[12] = args[5];
+	scsi_cmd[13] = args[6] & 0x4f;
 	scsi_cmd[14] = args[0];
 
 	/* Good values for timeout and retries?  Values below

-- 
Mark Lord
Real-Time Remedies Inc.
mlord@pobox.com