[PATCH] USB: yurex: fix control-URB timeout handling

From: Johan Hovold <johan@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, Johan Hovold <johan@kernel.org>,
	syzbot+e87ebe0f7913f71f2ea5@syzkaller.appspotmail.com,
	stable <stable@vger.kernel.org>
Subject: [PATCH] USB: yurex: fix control-URB timeout handling
Date: Mon, 14 Dec 2020 11:44:44 +0100	[thread overview]
Message-ID: <20201214104444.28386-1-johan@kernel.org> (raw)
In-Reply-To: <000000000000e2186705b65e671f@google.com>

Make sure to always cancel the control URB in write() so that it can be
reused after a timeout or spurious CMD_ACK.

Currently any further write requests after a timeout would fail after
triggering a WARN() in usb_submit_urb() when attempting to submit the
already active URB.

Reported-by: syzbot+e87ebe0f7913f71f2ea5@syzkaller.appspotmail.com
Fixes: 6bc235a2e24a ("USB: add driver for Meywa-Denki & Kayac YUREX")
Cc: stable <stable@vger.kernel.org>     # 2.6.37
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/yurex.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c
index 73ebfa6e9715..c640f98d20c5 100644
--- a/drivers/usb/misc/yurex.c
+++ b/drivers/usb/misc/yurex.c
@@ -496,6 +496,9 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer,
 		timeout = schedule_timeout(YUREX_WRITE_TIMEOUT);
 	finish_wait(&dev->waitq, &wait);
 
+	/* make sure URB is idle after timeout or (spurious) CMD_ACK */
+	usb_kill_urb(dev->cntl_urb);
+
 	mutex_unlock(&dev->io_mutex);
 
 	if (retval < 0) {
-- 
2.26.2

