[PATCH 5.4 10/92] usb: gadget: u_serial: add missing port entry locking

From: Greg Kroah-Hartman
Date: Wed Dec 11 2019 - 10:07:27 EST


From: MichaÅ MirosÅaw <mirq-linux@xxxxxxxxxxxx>

commit daf82bd24e308c5a83758047aff1bd81edda4f11 upstream.

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

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: MichaÅ MirosÅaw <mirq-linux@xxxxxxxxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Tested-by: Ladislav Michl <ladis@xxxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/usb/gadget/function/u_serial.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1239,8 +1239,10 @@ 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;
}