Re: [BUG] KASAN: slab-use-after-free in dev_driver_string from chaoskey_release

[Oliver Neukum]

On 07.06.26 04:29, Alan Stern wrote:
 
> The simple explanation is that the chaoskey_release() routine contains
> debugging statements that reference an interface for the USB device even
> after that data structure may have been deallocated.  Since they are
> merely debugging statements, the simplest solution to the problem is to
> get rid of them.
>
> That's what the patch below does.  You can try it out and see if it
> works.

Hi,

correct but it misses the same issue in disconnect.
You need this one on top.

	Regards
		Oliver
From 5864a7f4580707a39e3f5881ce31289095984dff Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@xxxxxxxx>
Date: Mon, 8 Jun 2026 13:20:35 +0200
Subject: [PATCH] usb: misc: chaoskey: fix UAF in disconnect

disconnect has the same issue as release.
The debug output refers to a potentially freed device.
Just remove it.

Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
---
 drivers/usb/misc/chaoskey.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index bf4d9294c7c9..0df337089618 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -222,12 +222,9 @@ static void chaoskey_disconnect(struct usb_interface *interface)
 {
 	struct chaoskey	*dev;
 
-	usb_dbg(interface, "disconnect");
 	dev = usb_get_intfdata(interface);
-	if (!dev) {
-		usb_dbg(interface, "disconnect failed - no dev");
+	if (!dev)
 		return;
-	}
 
 	if (dev->hwrng_registered)
 		hwrng_unregister(&dev->hwrng);
@@ -248,7 +245,6 @@ static void chaoskey_disconnect(struct usb_interface *interface)
 		mutex_unlock(&dev->lock);
 
 	mutex_unlock(&chaoskey_list_lock);
-	usb_dbg(interface, "disconnect done");
 }
 
 static int chaoskey_open(struct inode *inode, struct file *file)
-- 
2.54.0