linux-kernel - [PATCH 4.2.y-ckt 202/305] ses: fix additional element traversal bug

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Message-Id: <1452902519-2754-203-git-send-email-kamal@canonical.com>
Date:	Fri, 15 Jan 2016 16:00:16 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	James Bottomley <James.Bottomley@...senPartnership.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 202/305] ses: fix additional element traversal bug

4.2.8-ckt2 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: James Bottomley <James.Bottomley@...senPartnership.com>

commit 5e1033561da1152c57b97ee84371dba2b3d64c25 upstream.

KASAN found that our additional element processing scripts drop off
the end of the VPD page into unallocated space.  The reason is that
not every element has additional information but our traversal
routines think they do, leading to them expecting far more additional
information than is present.  Fix this by adding a gate to the
traversal routine so that it only processes elements that are expected
to have additional information (list is in SES-2 section 6.1.13.1:
Additional Element Status diagnostic page overview)

Reported-by: Pavel Tikhomirov <ptikhomirov@...tuozzo.com>
Tested-by: Pavel Tikhomirov <ptikhomirov@...tuozzo.com>
Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/scsi/ses.c        | 10 +++++++++-
 include/linux/enclosure.h |  4 ++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index 7d9cec5..044d064 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -559,7 +559,15 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
 			if (desc_ptr)
 				desc_ptr += len;
 
-			if (addl_desc_ptr)
+			if (addl_desc_ptr &&
+			    /* only find additional descriptions for specific devices */
+			    (type_ptr[0] == ENCLOSURE_COMPONENT_DEVICE ||
+			     type_ptr[0] == ENCLOSURE_COMPONENT_ARRAY_DEVICE ||
+			     type_ptr[0] == ENCLOSURE_COMPONENT_SAS_EXPANDER ||
+			     /* these elements are optional */
+			     type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_TARGET_PORT ||
+			     type_ptr[0] == ENCLOSURE_COMPONENT_SCSI_INITIATOR_PORT ||
+			     type_ptr[0] == ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS))
 				addl_desc_ptr += addl_desc_ptr[1] + 2;
 
 		}
diff --git a/include/linux/enclosure.h b/include/linux/enclosure.h
index 7be22da..a4cf57c 100644
--- a/include/linux/enclosure.h
+++ b/include/linux/enclosure.h
@@ -29,7 +29,11 @@
 /* A few generic types ... taken from ses-2 */
 enum enclosure_component_type {
 	ENCLOSURE_COMPONENT_DEVICE = 0x01,
+	ENCLOSURE_COMPONENT_CONTROLLER_ELECTRONICS = 0x07,
+	ENCLOSURE_COMPONENT_SCSI_TARGET_PORT = 0x14,
+	ENCLOSURE_COMPONENT_SCSI_INITIATOR_PORT = 0x15,
 	ENCLOSURE_COMPONENT_ARRAY_DEVICE = 0x17,
+	ENCLOSURE_COMPONENT_SAS_EXPANDER = 0x18,
 };
 
 /* ses-2 common element status */
-- 
1.9.1