watchdog: pcwd_usb: Use allocated buffer for usb_control_msg

usb_control_msg() must use a dma-capable buffer.

This fixes the following error reported by smatch:

drivers/watchdog/pcwd_usb.c:257 usb_pcwd_send_command() error: doing dma on the
stack (buf)

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/watchdog/pcwd_usb.c b/drivers/watchdog/pcwd_usb.c
index 7b14d1847927..115a0ebebf4a 100644
--- a/drivers/watchdog/pcwd_usb.c
+++ b/drivers/watchdog/pcwd_usb.c
@@ -235,13 +235,17 @@ static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
                 unsigned char cmd, unsigned char *msb, unsigned char *lsb)
 {
         int got_response, count;
-        unsigned char buf[6];
+        unsigned char *buf;
 
         /* We will not send any commands if the USB PCWD device does
          * not exist */
         if ((!usb_pcwd) || (!usb_pcwd->exists))
                 return -1;
 
+        buf = kmalloc(6, GFP_KERNEL);
+        if (buf == NULL)
+                return 0;
+
         /* The USB PC Watchdog uses a 6 byte report format.
          * The board currently uses only 3 of the six bytes of the report. */
         buf[0] = cmd;                   /* Byte 0 = CMD */
@@ -277,6 +281,8 @@ static int usb_pcwd_send_command(struct usb_pcwd_private *usb_pcwd,
                 *lsb = usb_pcwd->cmd_data_lsb;
         }
 
+        kfree(buf);
+
         return got_response;
 }