linux-kernel - [PATCH] usb: gadget: serial: fix oops when data rx'd after close

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Message-Id: <20170816203010.22993-1-swarren@wwwdotorg.org>
Date:   Wed, 16 Aug 2017 14:30:10 -0600
From:   Stephen Warren <swarren@...dotorg.org>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stephen Warren <swarren@...dia.com>
Subject: [PATCH] usb: gadget: serial: fix oops when data rx'd after close

From: Stephen Warren <swarren@...dia.com>

When the gadget serial device has no associated TTY, do not pass any
received data into the TTY layer for processing; simply drop it instead.
This prevents the TTY layer from calling back into the gadget serial
driver, which will then crash in e.g. gs_write_room() due to lack of
gadget serial device to TTY association (i.e. a NULL pointer dereference).

Signed-off-by: Stephen Warren <swarren@...dia.com>
---
 drivers/usb/gadget/function/u_serial.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index 9b0805f55ad7..16bb24a047d9 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -537,7 +537,7 @@ static void gs_rx_push(unsigned long _port)
 		}
 
 		/* push data to (open) tty */
-		if (req->actual) {
+		if (req->actual & tty) {
 			char		*packet = req->buf;
 			unsigned	size = req->actual;
 			unsigned	n;
-- 
2.14.1