hid: thingm: reorder calls in thingm_probe

When reviewing another thingm patch Benjamin Tissoires pointed out
the following: "The problem here is that hid_hw_start() is called
before thingm_version() which allows user space to briefly introduce
races between thingm_version() and any hidraw requests.
The mutex will not help here as it is initialized after hid_hw_start()
and only used for protecting the concurrent access of the rgb."

Avoid this possible issue by calling hid_hw_start() later in the
probe function.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-thingm.c b/drivers/hid/hid-thingm.c
index f4196ac25a649c7287470f7b581d82e1101faa7c..847a497cd47245223185665839fb9e2452a7665a 100644 (file)
--- a/drivers/hid/hid-thingm.c
+++ b/drivers/hid/hid-thingm.c
@@ -216,17 +216,13 @@ static int thingm_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
        err = hid_parse(hdev);
        if (err)
-               goto error;
-
-       err = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
-       if (err)
-               goto error;
+               return err;
 
        mutex_init(&tdev->lock);
 
        err = thingm_version(tdev);
        if (err)
-               goto stop;
+               return err;
 
        hid_dbg(hdev, "firmware version: %c.%c\n",
                        tdev->version.major, tdev->version.minor);
@@ -237,17 +233,18 @@ static int thingm_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
        if (!tdev->fwinfo) {
                hid_err(hdev, "unsupported firmware %c\n", tdev->version.major);
-               err = -ENODEV;
-               goto stop;
+               return -ENODEV;
        }
 
        tdev->rgb = devm_kzalloc(&hdev->dev,
                        sizeof(struct thingm_rgb) * tdev->fwinfo->numrgb,
                        GFP_KERNEL);
-       if (!tdev->rgb) {
-               err = -ENOMEM;
-               goto stop;
-       }
+       if (!tdev->rgb)
+               return -ENOMEM;
+
+       err = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
+       if (err)
+               return err;
 
        for (i = 0; i < tdev->fwinfo->numrgb; ++i) {
                struct thingm_rgb *rgb = tdev->rgb + i;
@@ -255,15 +252,13 @@ static int thingm_probe(struct hid_device *hdev, const struct hid_device_id *id)
                rgb->tdev = tdev;
                rgb->num = tdev->fwinfo->first + i;
                err = thingm_init_rgb(rgb);
-               if (err)
-                       goto stop;
+               if (err) {
+                       hid_hw_stop(hdev);
+                       return err;
+               }
        }
 
        return 0;
-stop:
-       hid_hw_stop(hdev);
-error:
-       return err;
 }
 
 static const struct hid_device_id thingm_table[] = {