[PATCH 2/6] USB: iowarrior: fix use-after-free on release

From: Johan Hovold <johan@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oliver Neukum <oneukum@suse.com>,
	Valentin Vidic <vvidic@valentin-vidic.from.hr>,
	linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	Johan Hovold <johan@kernel.org>, stable <stable@vger.kernel.org>
Subject: [PATCH 2/6] USB: iowarrior: fix use-after-free on release
Date: Wed,  9 Oct 2019 12:48:42 +0200	[thread overview]
Message-ID: <20191009104846.5925-3-johan@kernel.org> (raw)
In-Reply-To: <20191009104846.5925-1-johan@kernel.org>

The driver was accessing its struct usb_interface from its release()
callback without holding a reference. This would lead to a
use-after-free whenever debugging was enabled and the device was
disconnected while its character device was open.

Fixes: 549e83500b80 ("USB: iowarrior: Convert local dbg macro to dev_dbg")
Cc: stable <stable@vger.kernel.org>     # 3.16
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/iowarrior.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/misc/iowarrior.c b/drivers/usb/misc/iowarrior.c
index 4fe1d3267b3c..6841267820c6 100644
--- a/drivers/usb/misc/iowarrior.c
+++ b/drivers/usb/misc/iowarrior.c
@@ -243,6 +243,7 @@ static inline void iowarrior_delete(struct iowarrior *dev)
 	kfree(dev->int_in_buffer);
 	usb_free_urb(dev->int_in_urb);
 	kfree(dev->read_queue);
+	usb_put_intf(dev->interface);
 	kfree(dev);
 }
 
@@ -764,7 +765,7 @@ static int iowarrior_probe(struct usb_interface *interface,
 	init_waitqueue_head(&dev->write_wait);
 
 	dev->udev = udev;
-	dev->interface = interface;
+	dev->interface = usb_get_intf(interface);
 
 	iface_desc = interface->cur_altsetting;
 	dev->product_id = le16_to_cpu(udev->descriptor.idProduct);
-- 
2.23.0

