[PATCH] staging: comedi: drivers: usbduxsigma.c: fix DMA buffers on stack

[Kumar Amit Mehta]

This patch fixes an instance of DMA buffer on stack(being passed to
usb_control_msg)for the USB-DUXsigma Board driver. Found using smatch.

Signed-off-by: Kumar Amit Mehta <gmate.a...@gmail.com>
---
 drivers/staging/comedi/drivers/usbduxsigma.c |   37 +++++++++++++++++---------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c 
b/drivers/staging/comedi/drivers/usbduxsigma.c
index dc6b017..46137e8 100644
--- a/drivers/staging/comedi/drivers/usbduxsigma.c
+++ b/drivers/staging/comedi/drivers/usbduxsigma.c
@@ -681,10 +681,14 @@ static void usbduxsub_ao_IsocIrq(struct urb *urb)
 static int usbduxsub_start(struct usbduxsub *usbduxsub)
 {
        int errcode = 0;
-       uint8_t local_transfer_buffer[16];
-
+       uint8_t *local_transfer_buffer;
+       local_transfer_buffer = kmalloc(16, GFP_KERNEL);
+       if (!local_transfer_buffer) {
+               errcode = -ENOMEM;
+               goto exit;
+       }
        /* 7f92 to zero */
-       local_transfer_buffer[0] = 0;
+       *local_transfer_buffer = 0;
        errcode = usb_control_msg(usbduxsub->usbdev,
                                  /* create a pipe for a control transfer */
                                  usb_sndctrlpipe(usbduxsub->usbdev, 0),
@@ -702,22 +706,28 @@ static int usbduxsub_start(struct usbduxsub *usbduxsub)
                                  1,
                                  /* Timeout */
                                  BULK_TIMEOUT);
-       if (errcode < 0) {
+       if (errcode < 0)
                dev_err(&usbduxsub->interface->dev,
                        "comedi_: control msg failed (start)\n");
-               return errcode;
-       }
-       return 0;
+
+       kfree(local_transfer_buffer);
+exit:
+       return errcode;
 }
 
 static int usbduxsub_stop(struct usbduxsub *usbduxsub)
 {
        int errcode = 0;
 
-       uint8_t local_transfer_buffer[16];
+       uint8_t *local_transfer_buffer;
+       local_transfer_buffer = kmalloc(16, GFP_KERNEL);
+       if (!local_transfer_buffer) {
+               errcode = -ENOMEM;
+               goto exit;
+       }
 
        /* 7f92 to one */
-       local_transfer_buffer[0] = 1;
+       *local_transfer_buffer = 1;
        errcode = usb_control_msg(usbduxsub->usbdev,
                                  usb_sndctrlpipe(usbduxsub->usbdev, 0),
                                  /* bRequest, "Firmware" */
@@ -732,12 +742,13 @@ static int usbduxsub_stop(struct usbduxsub *usbduxsub)
                                  1,
                                  /* Timeout */
                                  BULK_TIMEOUT);
-       if (errcode < 0) {
+       if (errcode < 0)
                dev_err(&usbduxsub->interface->dev,
                        "comedi_: control msg failed (stop)\n");
-               return errcode;
-       }
-       return 0;
+
+       kfree(local_transfer_buffer);
+exit:
+       return errcode;
 }
 
 static int usbduxsub_upload(struct usbduxsub *usbduxsub,
-- 
1.7.9.5

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