[PATCH v5 5/5] dvb-usb-v2/gl861: ensure USB message buffers DMA'able

[tskd08]

From: Akihiro Tsukada <tsk...@gmail.com>

i2c message buf might be on stack.

Signed-off-by: Akihiro Tsukada <tsk...@gmail.com>
---
Changes since v4:
- none

 drivers/media/usb/dvb-usb-v2/gl861.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/media/usb/dvb-usb-v2/gl861.c 
b/drivers/media/usb/dvb-usb-v2/gl861.c
index cdd7bfcb883..47b614da807 100644
--- a/drivers/media/usb/dvb-usb-v2/gl861.c
+++ b/drivers/media/usb/dvb-usb-v2/gl861.c
@@ -22,6 +22,8 @@ static int gl861_i2c_msg(struct dvb_usb_device *d, u8 addr,
        u16 value = addr << (8 + 1);
        int wo = (rbuf == NULL || rlen == 0); /* write-only */
        u8 req, type;
+       u8 *buf;
+       int ret;
 
        if (wo) {
                req = GL861_REQ_I2C_WRITE;
@@ -44,11 +46,23 @@ static int gl861_i2c_msg(struct dvb_usb_device *d, u8 addr,
                                KBUILD_MODNAME, wlen);
                return -EINVAL;
        }
-
+       buf = NULL;
+       if (rlen > 0) {
+               buf = kmalloc(rlen, GFP_KERNEL);
+               if (!buf)
+                       return -ENOMEM;
+       }
        usleep_range(1000, 2000); /* avoid I2C errors */
 
-       return usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
-                              value, index, rbuf, rlen, 2000);
+       ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
+                             value, index, buf, rlen, 2000);
+       if (rlen > 0) {
+               if (ret > 0)
+                       memcpy(rbuf, buf, rlen);
+               kfree(buf);
+       }
+
+       return ret;
 }
 
 /* Friio specific I2C read/write */
-- 
2.17.0