cxusb: Use a dma capable buffer also for reading

commit 3f190e3aec212fc8c61e202c51400afa7384d4bc upstream.

Commit 17ce039b4e54 ("[media] cxusb: don't do DMA on stack")
added a kmalloc'ed bounce buffer for writes, but missed to do the same
for reads. As the read only happens after the write is finished, we can
reuse the same buffer.

As dvb_usb_generic_rw handles a read length of 0 by itself, avoid calling
it using the dvb_usb_generic_read wrapper function.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/media/usb/dvb-usb/cxusb.c b/drivers/media/usb/dvb-usb/cxusb.c
index 243403081fa53f2860a5b67469593b5ecffae62a..9fd43a37154cedb24576903a5e2eceae99719227 100644 (file)
--- a/drivers/media/usb/dvb-usb/cxusb.c
+++ b/drivers/media/usb/dvb-usb/cxusb.c
@@ -59,23 +59,24 @@ static int cxusb_ctrl_msg(struct dvb_usb_device *d,
                          u8 cmd, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
 {
        struct cxusb_state *st = d->priv;
-       int ret, wo;
+       int ret;
 
        if (1 + wlen > MAX_XFER_SIZE) {
                warn("i2c wr: len=%d is too big!\n", wlen);
                return -EOPNOTSUPP;
        }
 
-       wo = (rbuf == NULL || rlen == 0); /* write-only */
+       if (rlen > MAX_XFER_SIZE) {
+               warn("i2c rd: len=%d is too big!\n", rlen);
+               return -EOPNOTSUPP;
+       }
 
        mutex_lock(&d->data_mutex);
        st->data[0] = cmd;
        memcpy(&st->data[1], wbuf, wlen);
-       if (wo)
-               ret = dvb_usb_generic_write(d, st->data, 1 + wlen);
-       else
-               ret = dvb_usb_generic_rw(d, st->data, 1 + wlen,
-                                        rbuf, rlen, 0);
+       ret = dvb_usb_generic_rw(d, st->data, 1 + wlen, st->data, rlen, 0);
+       if (!ret && rbuf && rlen)
+               memcpy(rbuf, st->data, rlen);
 
        mutex_unlock(&d->data_mutex);
        return ret;