[media] af9015: do not use buffers from stack for usb_bulk_msg()

WARNING: at lib/dma-debug.c:947 check_for_stack+0xa7/0xf0()
ehci-pci 0000:00:04.1: DMA-API: device driver maps memory fromstack

Reported-by: poma <pomidorabelisima@gmail.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/dvb-usb-v2/af9015.c

@@ -30,22 +30,22 @@ DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nr);
 
 static int af9015_ctrl_msg(struct dvb_usb_device *d, struct req_t *req)
 {
-#define BUF_LEN 63
 #define REQ_HDR_LEN 8 /* send header size */
 #define ACK_HDR_LEN 2 /* rece header size */
 	struct af9015_state *state = d_to_priv(d);
 	int ret, wlen, rlen;
-	u8 buf[BUF_LEN];
 	u8 write = 1;
 
-	buf[0] = req->cmd;
-	buf[1] = state->seq++;
-	buf[2] = req->i2c_addr;
-	buf[3] = req->addr >> 8;
-	buf[4] = req->addr & 0xff;
-	buf[5] = req->mbox;
-	buf[6] = req->addr_len;
-	buf[7] = req->data_len;
+	mutex_lock(&d->usb_mutex);
+
+	state->buf[0] = req->cmd;
+	state->buf[1] = state->seq++;
+	state->buf[2] = req->i2c_addr;
+	state->buf[3] = req->addr >> 8;
+	state->buf[4] = req->addr & 0xff;
+	state->buf[5] = req->mbox;
+	state->buf[6] = req->addr_len;
+	state->buf[7] = req->data_len;
 
 	switch (req->cmd) {
 	case GET_CONFIG:
@@ -55,14 +55,14 @@ static int af9015_ctrl_msg(struct dvb_usb_device *d, struct req_t *req)
 		break;
 	case READ_I2C:
 		write = 0;
-		buf[2] |= 0x01; /* set I2C direction */
+		state->buf[2] |= 0x01; /* set I2C direction */
 	case WRITE_I2C:
-		buf[0] = READ_WRITE_I2C;
+		state->buf[0] = READ_WRITE_I2C;
 		break;
 	case WRITE_MEMORY:
 		if (((req->addr & 0xff00) == 0xff00) ||
 		    ((req->addr & 0xff00) == 0xae00))
-			buf[0] = WRITE_VIRTUAL_MEMORY;
+			state->buf[0] = WRITE_VIRTUAL_MEMORY;
 	case WRITE_VIRTUAL_MEMORY:
 	case COPY_FIRMWARE:
 	case DOWNLOAD_FIRMWARE:
@@ -90,7 +90,7 @@ static int af9015_ctrl_msg(struct dvb_usb_device *d, struct req_t *req)
 	rlen = ACK_HDR_LEN;
 	if (write) {
 		wlen += req->data_len;
-		memcpy(&buf[REQ_HDR_LEN], req->data, req->data_len);
+		memcpy(&state->buf[REQ_HDR_LEN], req->data, req->data_len);
 	} else {
 		rlen += req->data_len;
 	}
@@ -99,22 +99,25 @@ static int af9015_ctrl_msg(struct dvb_usb_device *d, struct req_t *req)
 	if (req->cmd == DOWNLOAD_FIRMWARE || req->cmd == RECONNECT_USB)
 		rlen = 0;
 
-	ret = dvb_usbv2_generic_rw(d, buf, wlen, buf, rlen);
+	ret = dvb_usbv2_generic_rw_locked(d,
+			state->buf, wlen, state->buf, rlen);
 	if (ret)
 		goto error;
 
 	/* check status */
-	if (rlen && buf[1]) {
+	if (rlen && state->buf[1]) {
 		dev_err(&d->udev->dev, "%s: command failed=%d\n",
-				KBUILD_MODNAME, buf[1]);
+				KBUILD_MODNAME, state->buf[1]);
 		ret = -EIO;
 		goto error;
 	}
 
 	/* read request, copy returned data to return buf */
 	if (!write)
-		memcpy(req->data, &buf[ACK_HDR_LEN], req->data_len);
+		memcpy(req->data, &state->buf[ACK_HDR_LEN], req->data_len);
 error:
+	mutex_unlock(&d->usb_mutex);
+
 	return ret;
 }
 

drivers/media/usb/dvb-usb-v2/af9015.h

@@ -115,7 +115,9 @@ enum af9015_ir_mode {
 	AF9015_IR_MODE_POLLING, /* just guess */
 };
 
+#define BUF_LEN 63
 struct af9015_state {
+	u8 buf[BUF_LEN]; /* bulk USB control message */
 	u8 ir_mode;
 	u8 rc_repeat;
 	u32 rc_keycode;