[PATCH v2 3/3] scsi: sd: Fix interpretation of VPD B9h length

[Tyler Erickson <tyler.erickson@seagate.com>]

Fixing the interpretation of the length of the B9h VPD page
(concurrent positioning ranges). Adding 4 is necessary as
the first 4 bytes of the page is the header with page number
and length information. Adding 3 was likely a misinterpretation
of the SBC-5 specification which sets all offsets starting at zero.

This fixes the error in dmesg:
[ 9.014456] sd 1:0:0:0: [sda] Invalid Concurrent Positioning Ranges VPD page

Cc: stable@vger.kernel.org
Fixes: e815d36548f0 ("scsi: sd: add concurrent positioning ranges support")
Signed-off-by: Tyler Erickson <tyler.erickson@seagate.com>
Reviewed-by: Muhammad Ahmad <muhammad.ahmad@seagate.com>
Tested-by: Michael English <michael.english@seagate.com>
---
 drivers/scsi/sd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 749316462075..f25b0cc5dd21 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3072,7 +3072,7 @@ static void sd_read_cpr(struct scsi_disk *sdkp)
 		goto out;
 
 	/* We must have at least a 64B header and one 32B range descriptor */
-	vpd_len = get_unaligned_be16(&buffer[2]) + 3;
+	vpd_len = get_unaligned_be16(&buffer[2]) + 4;
 	if (vpd_len > buf_len || vpd_len < 64 + 32 || (vpd_len & 31)) {
 		sd_printk(KERN_ERR, sdkp,
 			  "Invalid Concurrent Positioning Ranges VPD page\n");
-- 
2.17.1