From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Date: Sat, 10 Aug 2019 08:42:48 +0000 (+0200)
Subject: usb: gadget: u_serial: add missing port entry locking
X-Git-Tag: v4.19.89~249
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c5a309dc42f1891c8c00a704d5d206702a047a42;p=thirdparty%2Fkernel%2Fstable.git

usb: gadget: u_serial: add missing port entry locking

commit daf82bd24e308c5a83758047aff1bd81edda4f11 upstream.

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

Cc: stable@vger.kernel.org
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 29436f75bbe06..d4d317db89df5 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -1246,8 +1246,10 @@ int gserial_alloc_line(unsigned char *line_num)
 				__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;
 	}