From c468a8aa790e0dfe0a7f8a39db282d39c2c00b46 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Thu, 8 Aug 2019 11:27:28 +0200
Subject: [PATCH] usb: iowarrior: fix deadlock on disconnect
Git-commit: c468a8aa790e0dfe0a7f8a39db282d39c2c00b46
Patch-mainline: v5.3-rc4
References: bsc#1051510

We have to drop the mutex before we close() upon disconnect()
as close() needs the lock. This is safe to do by dropping the
mutex as intfdata is already set to NULL, so open() will fail.

Fixes: 03f36e885fc26 ("USB: open disconnect race in iowarrior")
Reported-by: syzbot+a64a382964bf6c71a9c0@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20190808092728.23417-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/usb/misc/iowarrior.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index ba05dd80a020..f5bed9f29e56 100644
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -866,19 +866,20 @@ static void iowarrior_disconnect(struct usb_interface *interface)
 	dev = usb_get_intfdata(interface);
 	mutex_lock(&iowarrior_open_disc_lock);
 	usb_set_intfdata(interface, NULL);
+	/* prevent device read, write and ioctl */
+	dev->present = 0;
 
 	minor = dev->minor;
+	mutex_unlock(&iowarrior_open_disc_lock);
+	/* give back our minor - this will call close() locks need to be dropped at this point*/
 
-	/* give back our minor */
 	usb_deregister_dev(interface, &iowarrior_class);
 
 	mutex_lock(&dev->mutex);
 
 	/* prevent device read, write and ioctl */
-	dev->present = 0;
 
 	mutex_unlock(&dev->mutex);
-	mutex_unlock(&iowarrior_open_disc_lock);
 
 	if (dev->opened) {
 		/* There is a process that holds a filedescriptor to the device ,
-- 
2.16.4