scsi: sd: change allow_restart to bool in sysfs interface

BugLink: http://bugs.launchpad.net/bugs/1745052

[ Upstream commit 658e9a6d ]

/sys/class/scsi_disk/0:2:0:0/allow_restart can be changed to 0
unexpectedly by writing an invalid string such as the following:

echo asdf > /sys/class/scsi_disk/0:2:0:0/allow_restart
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/scsi/sd.c

@@ -259,6 +259,7 @@ static ssize_t
 allow_restart_store(struct device *dev, struct device_attribute *attr,
 		    const char *buf, size_t count)
 {
+	bool v;
 	struct scsi_disk *sdkp = to_scsi_disk(dev);
 	struct scsi_device *sdp = sdkp->device;
 
@@ -268,7 +269,10 @@ allow_restart_store(struct device *dev, struct device_attribute *attr,
 	if (sdp->type != TYPE_DISK)
 		return -EINVAL;
 
-	sdp->allow_restart = simple_strtoul(buf, NULL, 10);
+	if (kstrtobool(buf, &v))
+		return -EINVAL;
+
+	sdp->allow_restart = v;
 
 	return count;
 }