[PATCH 3.16 031/148] usb: gadget: u_serial: add missing port entry locking

Ben Hutchings
2020-02-08T18:38:05Z

From: Michał Mirosław <mirq-linux@rere.qmqm.pl>

commit daf82bd24e308c5a83758047aff1bd81edda4f11 upstream.

gserial_alloc_line() misses locking (for a release barrier) while
resetting port entry on TTY allocation failure. Fix this.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/gadget/u_serial.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/usb/gadget/u_serial.c
+++ b/drivers/usb/gadget/u_serial.c
@@ -1140,8 +1140,10 @@ int gserial_alloc_line(unsigned char *li
__func__, port_num, PTR_ERR(tty_dev));

ret = PTR_ERR(tty_dev);
+ mutex_lock(&ports[port_num].lock);
port = ports[port_num].port;
ports[port_num].port = NULL;
+ mutex_unlock(&ports[port_num].lock);
gserial_free_port(port);
goto err;
}