[PATCH resend v2 2/5] libata-scsi: fix read-only bits checking in ata_mselect_*()

[tom . ty89]

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

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.

Made it check every byte but mask the changeable bit.

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

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index eb5e8ff..4a4e6f1 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -3611,7 +3611,7 @@ static int ata_mselect_caching(struct ata_queued_cmd *qc,
        struct ata_taskfile *tf = &qc->tf;
        struct ata_device *dev = qc->dev;
        char mpage[CACHE_MPAGE_LEN];
-       u8 wce;
+       u8 wce, mask;
        int i;
 
        /*
@@ -3632,8 +3632,11 @@ 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;
-               if (mpage[i + 2] != buf[i]) {
+                       mask = 0xfb;
+               else
+                       mask = 0xff;
+
+               if ((mpage[i + 2] & mask) != (buf[i] & mask)) {
                        *fp = i;
                        return -EINVAL;
                }
@@ -3666,7 +3669,7 @@ static int ata_mselect_control(struct ata_queued_cmd *qc,
 {
        struct ata_device *dev = qc->dev;
        char mpage[CONTROL_MPAGE_LEN];
-       u8 d_sense;
+       u8 d_sense, mask;
        int i;
 
        /*
@@ -3687,8 +3690,11 @@ 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;
-               if (mpage[2 + i] != buf[i]) {
+                       mask = 0xfb;
+               else
+                       mask = 0xff;
+
+               if ((mpage[2 + i] & mask) != (buf[i] & mask)) {
                        *fp = i;
                        return -EINVAL;
                }
-- 
2.9.0

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