On Fri, Jan 17, 2020 at 10:50:26AM +0100, Johan Hovold wrote:
Check for NULL port data in the event handlers to avoid dereferencing a NULL pointer in the unlikely case where a port device isn't bound to a driver (e.g. after an allocation failure on port probe).
Fixes: f7a33e608d9a ("USB: serial: add quatech2 usb to serial driver") Cc: stable stable@vger.kernel.org # 3.5 Signed-off-by: Johan Hovold johan@kernel.org
drivers/usb/serial/quatech2.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c index a62981ca7a73..c76a2c0c32ff 100644 --- a/drivers/usb/serial/quatech2.c +++ b/drivers/usb/serial/quatech2.c @@ -470,6 +470,13 @@ static int get_serial_info(struct tty_struct *tty, static void qt2_process_status(struct usb_serial_port *port, unsigned char *ch) {
- struct qt2_port_private *port_priv;
- /* May be called from qt2_process_read_urb() for an unbound port. */
- port_priv = usb_get_serial_port_data(port);
- if (!port_priv)
return;
Where is the null dereference here? Will port be NULL somehow?
switch (*ch) { case QT2_LINE_STATUS: qt2_update_lsr(port, ch + 1); @@ -484,14 +491,27 @@ static void qt2_process_status(struct usb_serial_port *port, unsigned char *ch) static void qt2_process_xmit_empty(struct usb_serial_port *port, unsigned char *ch) {
- struct qt2_port_private *port_priv; int bytes_written;
- /* May be called from qt2_process_read_urb() for an unbound port. */
- port_priv = usb_get_serial_port_data(port);
- if (!port_priv)
return;- bytes_written = (int)(*ch) + (int)(*(ch + 1) << 4);
What's the harm in doing a pointless calculation here? Nothing seems to happen in this function at all.
} /* not needed, kept to document functionality */ static void qt2_process_flush(struct usb_serial_port *port, unsigned char *ch) {
- struct qt2_port_private *port_priv;
- /* May be called from qt2_process_read_urb() for an unbound port. */
- port_priv = usb_get_serial_port_data(port);
- if (!port_priv)
return;- return;
}
This whole function can just be removed, right?
thanks,
greg k-h