linux-kernel - [PATCH v6 1/7] usb: gadget: u_serial: add missing port entry locking

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Message-Id: <4f3ba23fd4e8963cf5651290a34be894aeedb570.1565426370.git.mirq-linux@rere.qmqm.pl>
Date:   Sat, 10 Aug 2019 10:42:48 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     linux-usb@...r.kernel.org
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 1/7] usb: gadget: u_serial: add missing port entry locking

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

Cc: stable@...r.kernel.org
Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Tested-by: Ladislav Michl <ladis@...ux-mips.org>

---
  v6: rebased on balbi/testing/next
  v5: no changes
  v4: no changes
  v3: cc-stable
  v2: no changes

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

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 65f634ec7fc2..bb1e2e1d0076 100644
--- 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 *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;
 	}
-- 
2.20.1