[PATCH 4.9 170/177] scsi: sd: change allow_restart to bool in sysfs interface

[Greg Kroah-Hartman]

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

------------------

From: weiping zhang <zhangweiping@xxxxxxxxxxxxxxx>


[ Upstream commit 658e9a6dc1126f21fa417cd213e1cdbff8be0ba2 ]

/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@xxxxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/scsi/sd.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -260,6 +260,7 @@ 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;
 
@@ -269,7 +270,10 @@ allow_restart_store(struct device *dev,
 	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;
 }