Re: [PATCH resend 2/5] libata-scsi: fix read-only bits checking in ata_mselect_*()

[Tom Yan]

This is actually a bit clumsy. Sending a rewritten version.

On 22 July 2016 at 02:41,   wrote:
> From: Tom Yan 
>
> Commit 7780081c1f04 ("libata-scsi: Set information sense field for
> invalid parameter") changed how ata_mselect_*() make sure read-only
> bits are not modified. The new implementation introduced a bug that
> the read-only bits in the byte that has a changeable bit will not
> be checked.
>
> Added the necessary check, with comments explaining the heuristic.
>
> Signed-off-by: Tom Yan 
>
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index eb5e8ff..ac90676 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3631,8 +3631,18 @@ static int ata_mselect_caching(struct ata_queued_cmd 
> *qc,
>  */
> ata_msense_caching(dev->id, mpage, false);
> for (i = 0; i < CACHE_MPAGE_LEN - 2; i++) {
> -   if (i == 0)
> -   continue;
> +   /* Check the first byte */
> +   if (i == 0) {
> +   /* except the WCE bit */
> +   if ((mpage[i + 2] & 0xfb) != (buf[i] & 0xfb)) {
> +   *fp = i;
> +   return -EINVAL;
> +   } else {
> +   continue;
> +   }
> +   }
> +
> +   /* Check the remaining bytes */
> if (mpage[i + 2] != buf[i]) {
> *fp = i;
> return -EINVAL;
> @@ -3686,8 +3696,18 @@ static int ata_mselect_control(struct ata_queued_cmd 
> *qc,
>  */
> ata_msense_control(dev, mpage, false);
> for (i = 0; i < CONTROL_MPAGE_LEN - 2; i++) {
> -   if (i == 0)
> -   continue;
> +   /* Check the first byte */
> +   if (i == 0) {
> +   /* except the D_SENSE bit */
> +   if ((mpage[i + 2] & 0xfb) != (buf[i] & 0xfb)) {
> +   *fp = i;
> +   return -EINVAL;
> +   } else {
> +   continue;
> +   }
> +   }
> +
> +   /* Check the remaining bytes */
> if (mpage[2 + i] != buf[i]) {
> *fp = i;
> return -EINVAL;
> --
> 2.9.0
>

[PATCH resend 2/5] libata-scsi: fix read-only bits checking in ata_mselect_*()

[tom . ty89]

From: Tom Yan 

Commit 7780081c1f04 ("libata-scsi: Set information sense field for
invalid parameter") changed how ata_mselect_*() make sure read-only
bits are not modified. The new implementation introduced a bug that
the read-only bits in the byte that has a changeable bit will not
be checked.

Added the necessary check, with comments explaining the heuristic.

Signed-off-by: Tom Yan 

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index eb5e8ff..ac90676 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3631,8 +3631,18 @@ static int ata_mselect_caching(struct ata_queued_cmd *qc,
 */
ata_msense_caching(dev->id, mpage, false);
for (i = 0; i < CACHE_MPAGE_LEN - 2; i++) {
-   if (i == 0)
-   continue;
+   /* Check the first byte */
+   if (i == 0) {
+   /* except the WCE bit */
+   if ((mpage[i + 2] & 0xfb) != (buf[i] & 0xfb)) {
+   *fp = i;
+   return -EINVAL;
+   } else {
+   continue;
+   }
+   }
+
+   /* Check the remaining bytes */
if (mpage[i + 2] != buf[i]) {
*fp = i;
return -EINVAL;
@@ -3686,8 +3696,18 @@ static int ata_mselect_control(struct ata_queued_cmd *qc,
 */
ata_msense_control(dev, mpage, false);
for (i = 0; i < CONTROL_MPAGE_LEN - 2; i++) {
-   if (i == 0)
-   continue;
+   /* Check the first byte */
+   if (i == 0) {
+   /* except the D_SENSE bit */
+   if ((mpage[i + 2] & 0xfb) != (buf[i] & 0xfb)) {
+   *fp = i;
+   return -EINVAL;
+   } else {
+   continue;
+   }
+   }
+
+   /* Check the remaining bytes */
if (mpage[2 + i] != buf[i]) {
*fp = i;
return -EINVAL;
-- 
2.9.0