[SCSI] Return VPD page length in scsi_vpd_inquiry()

We should be returning the number of bytes of the
requested VPD page in scsi_vpd_inquiry.
This makes it easier for the caller to verify the
required space.

[jejb: fix up mm warning spotted by Sergey]
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 2b12983d2b2d..b2526ad7b9a1 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -942,7 +942,7 @@ EXPORT_SYMBOL(scsi_track_queue_full);
  * This is an internal helper function.  You probably want to use
  * scsi_get_vpd_page instead.
  *
- * Returns 0 on success or a negative error number.
+ * Returns size of the vpd page on success or a negative error number.
  */
 static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
                                                         u8 page, unsigned len)
@@ -950,6 +950,9 @@ static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
         int result;
         unsigned char cmd[16];
 
+        if (len < 4)
+                return -EINVAL;
+
         cmd[0] = INQUIRY;
         cmd[1] = 1;             /* EVPD */
         cmd[2] = page;
@@ -964,13 +967,13 @@ static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
                                   len, NULL, 30 * HZ, 3, NULL);
         if (result)
-                return result;
+                return -EIO;
 
         /* Sanity check that we got the page back that we asked for */
         if (buffer[1] != page)
                 return -EIO;
 
-        return 0;
+        return get_unaligned_be16(&buffer[2]) + 4;
 }
 
 /**
@@ -997,18 +1000,18 @@ int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 
         /* Ask for all the pages supported by this device */
         result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
-        if (result)
+        if (result < 4)
                 goto fail;
 
         /* If the user actually wanted this page, we can skip the rest */
         if (page == 0)
                 return 0;
 
-        for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
-                if (buf[i + 4] == page)
+        for (i = 4; i < min(result, buf_len); i++)
+                if (buf[i] == page)
                         goto found;
 
-        if (i < buf[3] && i >= buf_len - 4)
+        if (i < result && i >= buf_len)
                 /* ran off the end of the buffer, give us benefit of doubt */
                 goto found;
         /* The device claims it doesn't support the requested page */
@@ -1016,7 +1019,7 @@ int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 
  found:
         result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
-        if (result)
+        if (result < 0)
                 goto fail;
 
         return 0;