[PATCH v5 1/2] libata-scsi: reject WRITE SAME (16) with n_block that exceeds limit

[PATCH v5 1/2] libata-scsi: reject WRITE SAME (16) with n_block that exceeds limit

[tom.ty89]

From: Tom Yan <tom.ty89@gmail.com>

Currently if a WRITE SAME (16) command is issued to the SATL with
"number of blocks" that is larger than the "Maximum write same length"
(which is the maximum number of blocks per TRIM command allowed in
libata, currently 65535 * 512 / 8 blocks), the SATL will accept the
command and translate it to a TRIM command with the upper limit.

However, according to SBC (as of sbc4r11.pdf), the "device server"
should terminate the command with "Invalid field in CDB" in that case.

Signed-off-by: Tom Yan <tom.ty89@gmail.com>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index bfec66f..a1f061a 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3305,7 +3305,11 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
 		goto invalid_param_len;
 
 	buf = page_address(sg_page(scsi_sglist(scmd)));
-	size = ata_set_lba_range_entries(buf, 512, block, n_block);
+
+	if (n_block <= 65535 * 512 / 8)
+		size = ata_set_lba_range_entries(buf, 512, block, n_block);
+	else
+		goto invalid_fld;
 
 	if (ata_ncq_enabled(dev) && ata_fpdma_dsm_supported(dev)) {
 		/* Newer devices support queued TRIM commands */
-- 
2.9.0

Re: [PATCH v5 1/2] libata-scsi: reject WRITE SAME (16) with n_block that exceeds limit

[Tejun Heo]

On Thu, Jul 07, 2016 at 01:19:05AM +0800, tom.ty89@gmail.com wrote:
> From: Tom Yan <tom.ty89@gmail.com>
> 
> Currently if a WRITE SAME (16) command is issued to the SATL with
> "number of blocks" that is larger than the "Maximum write same length"
> (which is the maximum number of blocks per TRIM command allowed in
> libata, currently 65535 * 512 / 8 blocks), the SATL will accept the
> command and translate it to a TRIM command with the upper limit.
> 
> However, according to SBC (as of sbc4r11.pdf), the "device server"
> should terminate the command with "Invalid field in CDB" in that case.
> 
> Signed-off-by: Tom Yan <tom.ty89@gmail.com>
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index bfec66f..a1f061a 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3305,7 +3305,11 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
>  		goto invalid_param_len;
>  
>  	buf = page_address(sg_page(scsi_sglist(scmd)));
> -	size = ata_set_lba_range_entries(buf, 512, block, n_block);
> +
> +	if (n_block <= 65535 * 512 / 8)
> +		size = ata_set_lba_range_entries(buf, 512, block, n_block);
> +	else
> +		goto invalid_fld;

This triggers compiler warning about @fp used w/o initializing it.  I
reverted the patch.  Can you please update the patch?

Thanks.

-- 
tejun