[PATCH 3.2 31/59] [media] ttusb2: Don't use stack variables for DMA

[Ben Hutchings]

3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Josh Boyer <jwbo...@redhat.com>

commit ff17999184ed13829bc14c3be412d980173dff40 upstream.

The ttusb2_msg function uses on-stack variables to submit commands to
dvb_usb_generic.  This eventually gets to the DMA api layer and will throw a
traceback if the debugging options are set.

This allocates the temporary buffer variables with kzalloc instead.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=734506

Signed-off-by: Josh Boyer <jwbo...@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mche...@redhat.com>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/media/dvb/dvb-usb/ttusb2.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

--- a/drivers/media/dvb/dvb-usb/ttusb2.c
+++ b/drivers/media/dvb/dvb-usb/ttusb2.c
@@ -75,10 +75,18 @@ static int ttusb2_msg(struct dvb_usb_dev
                u8 *wbuf, int wlen, u8 *rbuf, int rlen)
 {
        struct ttusb2_state *st = d->priv;
-       u8 s[wlen+4],r[64] = { 0 };
+       u8 *s, *r = NULL;
        int ret = 0;
 
-       memset(s,0,wlen+4);
+       s = kzalloc(wlen+4, GFP_KERNEL);
+       if (!s)
+               return -ENOMEM;
+
+       r = kzalloc(64, GFP_KERNEL);
+       if (!r) {
+               kfree(s);
+               return -ENOMEM;
+       }
 
        s[0] = 0xaa;
        s[1] = ++st->id;
@@ -94,12 +102,17 @@ static int ttusb2_msg(struct dvb_usb_dev
                r[2] != cmd ||
                (rlen > 0 && r[3] != rlen)) {
                warn("there might have been an error during control message 
transfer. (rlen = %d, was %d)",rlen,r[3]);
+               kfree(s);
+               kfree(r);
                return -EIO;
        }
 
        if (rlen > 0)
                memcpy(rbuf, &r[4], rlen);
 
+       kfree(s);
+       kfree(r);
+
        return 0;
 }