[patch 11/25] SCSI: ch: fix ch_remove oops

Greg KH
2008-08-04T21:39:12Z

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2.6.26-stable review patch. If anyone has any objections, please let us
know.

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From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

commit 3d164fb09bb5cb8a223eddf634fc0d355714fcfe upstream.

The following commit causes ch_remove oops:

commit 24b42566c3fcbb5a9011d1446783d0f5844ccd45
Author: Greg Kroah-Hartman <gregkh@suse.de>
Date: Fri May 16 17:55:12 2008 -0700

SCSI: fix race in device_create

There is a race from when a device is created with device_create() and
then the drvdata is set with a call to dev_set_drvdata() in which a
sysfs file could be open, yet the drvdata will be NULL, causing all
sorts of bad things to happen.

This patch fixes the problem by using the new function,
device_create_drvdata(). It fixes the problem in all of the scsi
drivers that need it.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

The problem is ch_probe stores ch's private data at a wrong place.

We need to store it at scsi_device->sdev_gendev but the above patch
stores it at device struct that device_create_drvdata returns. So we
hit an oops when ch_remove accesses
scsi_device->sdev_gendev->driver_data, which is NULL.

Actually, there wasn't a race because ch doesn't create sysfs files
with device struct that device_create returns. This patch puts back
dev_set_drvdata() to set ch's private data properly.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/scsi/ch.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/scsi/ch.c
+++ b/drivers/scsi/ch.c
@@ -926,6 +926,7 @@ static int ch_probe(struct device *dev)
if (init)
ch_init_elem(ch);

+ dev_set_drvdata(dev, ch);
sdev_printk(KERN_INFO, sd, "Attached scsi changer %s\n", ch->name);

return 0;

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