patch "USB: chaoskey: fix use-after-free on release" added to usb-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    USB: chaoskey: fix use-after-free on release

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From 93ddb1f56ae102f14f9e46a9a9c8017faa970003 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 9 Oct 2019 17:38:45 +0200
Subject: USB: chaoskey: fix use-after-free on release

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

Fixes: 66e3e591891d ("usb: Add driver for Altus Metrum ChaosKey device (v2)")
Cc: stable <stable@vger.kernel.org>     # 4.1
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20191009153848.8664-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/misc/chaoskey.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index cf5828ce927a..34e6cd6f40d3 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -98,6 +98,7 @@ static void chaoskey_free(struct chaoskey *dev)
 		usb_free_urb(dev->urb);
 		kfree(dev->name);
 		kfree(dev->buf);
+		usb_put_intf(dev->interface);
 		kfree(dev);
 	}
 }
@@ -145,6 +146,8 @@ static int chaoskey_probe(struct usb_interface *interface,
 	if (dev == NULL)
 		goto out;
 
+	dev->interface = usb_get_intf(interface);
+
 	dev->buf = kmalloc(size, GFP_KERNEL);
 
 	if (dev->buf == NULL)
@@ -174,8 +177,6 @@ static int chaoskey_probe(struct usb_interface *interface,
 			goto out;
 	}
 
-	dev->interface = interface;
-
 	dev->in_ep = in_ep;
 
 	if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)
-- 
2.23.0