[PATCH v3] usb: misc: legousbtower: Fix buffers on stack

[Maksim Salau <maksim.salau@gmail.com>]

Allocate buffers on HEAP instead of STACK for local structures
that are to be received using usb_control_msg().

Signed-off-by: Maksim Salau <maksim.salau@gmail.com>

---
  Changes in v3:
   * rebased against usb-next;
   * removed Tested-by: Alfredo Rafael Vicente Boix <alviboi@gmail.com>;
   * removed Cc: stable@vger.kernel.org
     since this patch doesn't apply against v4.10.12
  Changes in v2:
   * made checkpatch happy with the format string passed to dev_info
     in tower_probe() (merged two parts into a single string literal);
   * changed commit message to better reflect location of the module;
     was: USB: legousbtower: Fix buffers on stack;
   * added Tested-by: Alfredo Rafael Vicente Boix <alviboi@gmail.com>
     and Cc: stable@vger.kernel.org

 drivers/usb/misc/legousbtower.c | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/misc/legousbtower.c b/drivers/usb/misc/legousbtower.c
index 201c9c3..aa3c280 100644
--- a/drivers/usb/misc/legousbtower.c
+++ b/drivers/usb/misc/legousbtower.c
@@ -317,9 +317,16 @@ static int tower_open (struct inode *inode, struct file *file)
 	int subminor;
 	int retval = 0;
 	struct usb_interface *interface;
-	struct tower_reset_reply reset_reply;
+	struct tower_reset_reply *reset_reply;
 	int result;
 
+	reset_reply = kmalloc(sizeof(*reset_reply), GFP_KERNEL);
+
+	if (!reset_reply) {
+		retval = -ENOMEM;
+		goto exit;
+	}
+
 	nonseekable_open(inode, file);
 	subminor = iminor(inode);
 
@@ -364,8 +371,8 @@ static int tower_open (struct inode *inode, struct file *file)
 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 				  0,
 				  0,
-				  &reset_reply,
-				  sizeof(reset_reply),
+				  reset_reply,
+				  sizeof(*reset_reply),
 				  1000);
 	if (result < 0) {
 		dev_err(&dev->udev->dev,
@@ -406,6 +413,7 @@ static int tower_open (struct inode *inode, struct file *file)
 	mutex_unlock(&dev->lock);
 
 exit:
+	kfree(reset_reply);
 	return retval;
 }
 
@@ -806,7 +814,7 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
 	struct device *idev = &interface->dev;
 	struct usb_device *udev = interface_to_usbdev(interface);
 	struct lego_usb_tower *dev = NULL;
-	struct tower_get_version_reply get_version_reply;
+	struct tower_get_version_reply *get_version_reply = NULL;
 	int retval = -ENOMEM;
 	int result;
 
@@ -871,6 +879,13 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
 	dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 	dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 
+	get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
+
+	if (!get_version_reply) {
+		retval = -ENOMEM;
+		goto error;
+	}
+
 	/* get the firmware version and log it */
 	result = usb_control_msg (udev,
 				  usb_rcvctrlpipe(udev, 0),
@@ -878,18 +893,19 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
 				  USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 				  0,
 				  0,
-				  &get_version_reply,
-				  sizeof(get_version_reply),
+				  get_version_reply,
+				  sizeof(*get_version_reply),
 				  1000);
 	if (result < 0) {
 		dev_err(idev, "LEGO USB Tower get version control request failed\n");
 		retval = result;
 		goto error;
 	}
-	dev_info(&interface->dev, "LEGO USB Tower firmware version is %d.%d "
-		 "build %d\n", get_version_reply.major,
-		 get_version_reply.minor,
-		 le16_to_cpu(get_version_reply.build_no));
+	dev_info(&interface->dev,
+		 "LEGO USB Tower firmware version is %d.%d build %d\n",
+		 get_version_reply->major,
+		 get_version_reply->minor,
+		 le16_to_cpu(get_version_reply->build_no));
 
 	/* we can register the device now, as it is ready */
 	usb_set_intfdata (interface, dev);
@@ -913,6 +929,7 @@ static int tower_probe (struct usb_interface *interface, const struct usb_device
 	return retval;
 
 error:
+	kfree(get_version_reply);
 	tower_delete(dev);
 	return retval;
 }
-- 
2.9.3