USB: mos7720: fix DMA to stack

The read_mos_reg function is called with stack-allocated buffers, which
must not be used for control messages.

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

diff --git a/drivers/usb/serial/mos7720.c b/drivers/usb/serial/mos7720.c
index cc0e54345df98c03621949fab2bdc91b7a90af3e..7752cffbf2bc3ea24e72d91579b50f0c33c72220 100644 (file)
--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -227,11 +227,22 @@ static int read_mos_reg(struct usb_serial *serial, unsigned int serial_portnum,
        __u8 requesttype = (__u8)0xc0;
        __u16 index = get_reg_index(reg);
        __u16 value = get_reg_value(reg, serial_portnum);
-       int status = usb_control_msg(usbdev, pipe, request, requesttype, value,
-                                    index, data, 1, MOS_WDR_TIMEOUT);
-       if (status < 0)
+       u8 *buf;
+       int status;
+
+       buf = kmalloc(1, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       status = usb_control_msg(usbdev, pipe, request, requesttype, value,
+                                    index, buf, 1, MOS_WDR_TIMEOUT);
+       if (status == 1)
+               *data = *buf;
+       else if (status < 0)
                dev_err(&usbdev->dev,
                        "mos7720: usb_control_msg() failed: %d", status);
+       kfree(buf);
+
        return status;
 }