[PATCH 20/58] USB: mos7720: fix broken control requests

[Kamal Mostafa]

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

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

From: Johan Hovold <jhovold at gmail.com>

commit ef6c8c1d733e244f0499035be0dabe1f4ed98c6f upstream.

The parallel-port code of the drivers used a stack allocated
control-request buffer for asynchronous (and possibly deferred) control
requests. This not only violates the no-DMA-from-stack requirement but
could also lead to corrupt control requests being submitted.

Signed-off-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/serial/mos7720.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index d166d3a..397e028 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -91,6 +91,7 @@ struct urbtracker {
 	struct list_head        urblist_entry;
 	struct kref             ref_count;
 	struct urb              *urb;
+	struct usb_ctrlrequest	*setup;
 };
 
 enum mos7715_pp_modes {
@@ -272,6 +273,7 @@ static void destroy_urbtracker(struct kref *kref)
 	struct mos7715_parport *mos_parport = urbtrack->mos_parport;
 
 	usb_free_urb(urbtrack->urb);
+	kfree(urbtrack->setup);
 	kfree(urbtrack);
 	kref_put(&mos_parport->ref_count, destroy_mos_parport);
 }
@@ -356,7 +358,6 @@ static int write_parport_reg_nonblock(struct mos7715_parport *mos_parport,
 	struct urbtracker *urbtrack;
 	int ret_val;
 	unsigned long flags;
-	struct usb_ctrlrequest setup;
 	struct usb_serial *serial = mos_parport->serial;
 	struct usb_device *usbdev = serial->dev;
 
@@ -374,14 +375,20 @@ static int write_parport_reg_nonblock(struct mos7715_parport *mos_parport,
 		kfree(urbtrack);
 		return -ENOMEM;
 	}
-	setup.bRequestType = (__u8)0x40;
-	setup.bRequest = (__u8)0x0e;
-	setup.wValue = get_reg_value(reg, dummy);
-	setup.wIndex = get_reg_index(reg);
-	setup.wLength = 0;
+	urbtrack->setup = kmalloc(sizeof(*urbtrack->setup), GFP_KERNEL);
+	if (!urbtrack->setup) {
+		usb_free_urb(urbtrack->urb);
+		kfree(urbtrack);
+		return -ENOMEM;
+	}
+	urbtrack->setup->bRequestType = (__u8)0x40;
+	urbtrack->setup->bRequest = (__u8)0x0e;
+	urbtrack->setup->wValue = get_reg_value(reg, dummy);
+	urbtrack->setup->wIndex = get_reg_index(reg);
+	urbtrack->setup->wLength = 0;
 	usb_fill_control_urb(urbtrack->urb, usbdev,
 			     usb_sndctrlpipe(usbdev, 0),
-			     (unsigned char *)&setup,
+			     (unsigned char *)urbtrack->setup,
 			     NULL, 0, async_complete, urbtrack);
 	kref_init(&urbtrack->ref_count);
 	INIT_LIST_HEAD(&urbtrack->urblist_entry);
-- 
1.8.1.2