[SCSI] Revert "[SCSI] Retrieve the Caching mode page"

This reverts commit 24d720b726c1a85f1962831ac30ad4d2ef8276b1.

Previously we thought there was little possibility that devices would
crash with this, but some have been found.

Reported-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Luben Tuikov <ltuikov@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 16 insertions, 47 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 7ff61d76b4c5..b61ebec6bca7 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2027,14 +2027,10 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
         int old_rcd = sdkp->RCD;
         int old_dpofua = sdkp->DPOFUA;
 
-        if (sdp->skip_ms_page_8) {
-                if (sdp->type == TYPE_RBC)
-                        goto defaults;
-                else {
-                        modepage = 0x3F;
-                        dbd = 0;
-                }
-        } else if (sdp->type == TYPE_RBC) {
+        if (sdp->skip_ms_page_8)
+                goto defaults;
+
+        if (sdp->type == TYPE_RBC) {
                 modepage = 6;
                 dbd = 8;
         } else {
@@ -2062,11 +2058,13 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
          */
         if (len < 3)
                 goto bad_sense;
-        else if (len > SD_BUF_SIZE) {
-                sd_printk(KERN_NOTICE, sdkp, "Truncating mode parameter "
-                          "data from %d to %d bytes\n", len, SD_BUF_SIZE);
-                len = SD_BUF_SIZE;
-        }
+        if (len > 20)
+                len = 20;
+
+        /* Take headers and block descriptors into account */
+        len += data.header_length + data.block_descriptor_length;
+        if (len > SD_BUF_SIZE)
+                goto bad_sense;
 
         /* Get the data */
         res = sd_do_mode_sense(sdp, dbd, modepage, buffer, len, &data, &sshdr);
@@ -2074,45 +2072,16 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
         if (scsi_status_is_good(res)) {
                 int offset = data.header_length + data.block_descriptor_length;
 
-                while (offset < len) {
-                        u8 page_code = buffer[offset] & 0x3F;
-                        u8 spf       = buffer[offset] & 0x40;
-
-                        if (page_code == 8 || page_code == 6) {
-                                /* We're interested only in the first 3 bytes.
-                                 */
-                                if (len - offset <= 2) {
-                                        sd_printk(KERN_ERR, sdkp, "Incomplete "
-                                                  "mode parameter data\n");
-                                        goto defaults;
-                                } else {
-                                        modepage = page_code;
-                                        goto Page_found;
-                                }
-                        } else {
-                                /* Go to the next page */
-                                if (spf && len - offset > 3)
-                                        offset += 4 + (buffer[offset+2] << 8) +
-                                                buffer[offset+3];
-                                else if (!spf && len - offset > 1)
-                                        offset += 2 + buffer[offset+1];
-                                else {
-                                        sd_printk(KERN_ERR, sdkp, "Incomplete "
-                                                  "mode parameter data\n");
-                                        goto defaults;
-                                }
-                        }
+                if (offset >= SD_BUF_SIZE - 2) {
+                        sd_printk(KERN_ERR, sdkp, "Malformed MODE SENSE response\n");
+                        goto defaults;
                 }
 
-                if (modepage == 0x3F) {
-                        sd_printk(KERN_ERR, sdkp, "No Caching mode page "
-                                  "present\n");
-                        goto defaults;
-                } else if ((buffer[offset] & 0x3f) != modepage) {
+                if ((buffer[offset] & 0x3f) != modepage) {
                         sd_printk(KERN_ERR, sdkp, "Got wrong page\n");
                         goto defaults;
                 }
-        Page_found:
+
                 if (modepage == 8) {
                         sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);
                         sdkp->RCD = ((buffer[offset + 2] & 0x01) != 0);