linux-kernel - [34-longterm 013/196] ses: Avoid kernel panic when lun 0 is not mapped

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Message-Id: <1331597724-31358-14-git-send-email-paul.gortmaker@windriver.com>
Date:	Mon, 12 Mar 2012 20:12:21 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org,
	"Krishnasamy, Somasundaram" <Somasundaram.Krishnasamy@....com>,
	Babu Moger <babu.moger@....com>,
	James Bottomley <James.Bottomley@...e.de>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 013/196] ses: Avoid kernel panic when lun 0 is not mapped

From: "Krishnasamy, Somasundaram" <Somasundaram.Krishnasamy@....com>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit d1e12de804f9d8ad114786ca7c2ce593cba79891 upstream.

During device discovery, scsi mid layer sends INQUIRY command to LUN
0. If the LUN 0 is not mapped to host, it creates a temporary
scsi_device with LUN id 0 and sends REPORT_LUNS command to it. After
the REPORT_LUNS succeeds, it walks through the LUN table and adds each
LUN found to sysfs. At the end of REPORT_LUNS lun table scan, it will
delete the temporary scsi_device of LUN 0.

When scsi devices are added to sysfs, it calls add_dev function of all
the registered class interfaces. If ses driver has been registered,
ses_intf_add() of ses module will be called. This function calls
scsi_device_enclosure() to check the inquiry data for EncServ
bit. Since inquiry was not allocated for temporary LUN 0 scsi_device,
it will cause NULL pointer exception.

To fix the problem, sdev->inquiry is checked for NULL before reading it.

Signed-off-by: Somasundaram Krishnasamy <Somasundaram.Krishnasamy@....com>
Signed-off-by: Babu Moger <babu.moger@....com>
Signed-off-by: James Bottomley <James.Bottomley@...e.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 include/scsi/scsi_device.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d80b6db..558fa2f 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -451,7 +451,7 @@ static inline int scsi_device_qas(struct scsi_device *sdev)
 }
 static inline int scsi_device_enclosure(struct scsi_device *sdev)
 {
-	return sdev->inquiry[6] & (1<<6);
+	return sdev->inquiry ? (sdev->inquiry[6] & (1<<6)) : 1;
 }
 
 static inline int scsi_device_protection(struct scsi_device *sdev)
-- 
1.7.9.3

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