USB: mos7720: fix broken control requests

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.

Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index 51da424327b0..b01300164fc0 100644
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -90,6 +90,7 @@ struct urbtracker {
         struct list_head        urblist_entry;
         struct kref             ref_count;
         struct urb              *urb;
+        struct usb_ctrlrequest  *setup;
 };
 
 enum mos7715_pp_modes {
@@ -271,6 +272,7 @@ 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);
 }
@@ -355,7 +357,6 @@ 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;
 
@@ -373,14 +374,20 @@ 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);