[PATCH 4.1 17/86] [media] rtl28xxu: fix control message flaws

Greg Kroah-Hartman
2015-11-06T20:25:25Z

From: Antti Palosaari <crope@iki.fi>

commit d18ca5b7ceca0e9674cb4bb2ed476b0fcbb23ba2 upstream.

Add lock to prevent concurrent access for control message as control
message function uses shared buffer. Without the lock there may be
remote control polling which messes the buffer causing IO errors.
Increase buffer size and add check for maximum supported message
length.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=103391
Fixes: c56222a6b25c ("[media] rtl28xxu: move usb buffers to state")

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 15 +++++++++++++--
drivers/media/usb/dvb-usb-v2/rtl28xxu.h | 2 +-
2 files changed, 14 insertions(+), 3 deletions(-)

--- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
+++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
@@ -34,6 +34,14 @@ static int rtl28xxu_ctrl_msg(struct dvb_
unsigned int pipe;
u8 requesttype;

+ mutex_lock(&d->usb_mutex);
+
+ if (req->size > sizeof(dev->buf)) {
+ dev_err(&d->intf->dev, "too large message %u\n", req->size);
+ ret = -EINVAL;
+ goto err_mutex_unlock;
+ }
+
if (req->index & CMD_WR_FLAG) {
/* write */
memcpy(dev->buf, req->data, req->size);
@@ -50,14 +58,17 @@ static int rtl28xxu_ctrl_msg(struct dvb_
dvb_usb_dbg_usb_control_msg(d->udev, 0, requesttype, req->value,
req->index, dev->buf, req->size);
if (ret < 0)
- goto err;
+ goto err_mutex_unlock;

/* read request, copy returned data to return buf */
if (requesttype == (USB_TYPE_VENDOR | USB_DIR_IN))
memcpy(req->data, dev->buf, req->size);

+ mutex_unlock(&d->usb_mutex);
+
return 0;
-err:
+err_mutex_unlock:
+ mutex_unlock(&d->usb_mutex);
dev_dbg(&d->intf->dev, "failed=%d\n", ret);
return ret;
}
--- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.h
+++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.h
@@ -69,7 +69,7 @@

struct rtl28xxu_dev {
- u8 buf[28];
+ u8 buf[128];
u8 chip_id;
u8 tuner;
char *tuner_name;