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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Johan Hovold <johan@kernel.org>
Subject: [PATCH 4.9 55/92] USB: chaoskey: fix use-after-free on release
Date:   Wed, 16 Oct 2019 14:50:28 -0700
Message-Id: <20191016214838.410672267@linuxfoundation.org>
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From: Johan Hovold <johan@kernel.org>

commit 93ddb1f56ae102f14f9e46a9a9c8017faa970003 upstream.

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(-)

--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -108,6 +108,7 @@ static void chaoskey_free(struct chaoske
 		usb_free_urb(dev->urb);
 		kfree(dev->name);
 		kfree(dev->buf);
+		usb_put_intf(dev->interface);
 		kfree(dev);
 	}
 }
@@ -157,6 +158,8 @@ static int chaoskey_probe(struct usb_int
 	if (dev == NULL)
 		goto out;
 
+	dev->interface = usb_get_intf(interface);
+
 	dev->buf = kmalloc(size, GFP_KERNEL);
 
 	if (dev->buf == NULL)
@@ -190,8 +193,6 @@ static int chaoskey_probe(struct usb_int
 		strcat(dev->name, udev->serial);
 	}
 
-	dev->interface = interface;
-
 	dev->in_ep = in_ep;
 
 	if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)