[ 3.8.y.z extended stable ] Patch "[SCSI] sd: Fix potential out-of-bounds access" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Fri Sep 20 00:36:29 UTC 2013

This is a note to let you know that I have just added a patch titled

    [SCSI] sd: Fix potential out-of-bounds access

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see



>From c0536c5524ee2fadafdbbeea6f9e2dc23292f530 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern at rowland.harvard.edu>
Date: Fri, 6 Sep 2013 11:49:51 -0400
Subject: [SCSI] sd: Fix potential out-of-bounds access

commit 984f1733fcee3fbc78d47e26c5096921c5d9946a upstream.

This patch fixes an out-of-bounds error in sd_read_cache_type(), found
by Google's AddressSanitizer tool.  When the loop ends, we know that
"offset" lies beyond the end of the data in the buffer, so no Caching
mode page was found.  In theory it may be present, but the buffer size
is limited to 512 bytes.

Signed-off-by: Alan Stern <stern at rowland.harvard.edu>
Reported-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: James Bottomley <JBottomley at Parallels.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/scsi/sd.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a1dcdc3..bc108d2 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2421,14 +2421,9 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)

-		if (modepage == 0x3F) {
-			sd_printk(KERN_ERR, sdkp, "No Caching mode page "
-				  "present\n");
-			goto defaults;
-		} else if ((buffer[offset] & 0x3f) != modepage) {
-			sd_printk(KERN_ERR, sdkp, "Got wrong page\n");
-			goto defaults;
-		}
+		sd_printk(KERN_ERR, sdkp, "No Caching mode page found\n");
+		goto defaults;
 		if (modepage == 8) {
 			sdkp->WCE = ((buffer[offset + 2] & 0x04) != 0);

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