From: Lukas Wunner <lukas@wunner.de>
To: Oliver Neukum <oneukum@suse.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Jann Horn <jannh@google.com>,
Oleksij Rempel <o.rempel@pengutronix.de>,
netdev@vger.kernel.org, linux-usb@vger.kernel.org,
Andrew Lunn <andrew@lunn.ch>, Eric Dumazet <edumazet@google.com>,
Jacky Chou <jackychou@asix.com.tw>, Willy Tarreau <w@1wt.eu>,
Lino Sanfilippo <LinoSanfilippo@gmx.de>,
Philipp Rosenberger <p.rosenberger@kunbus.com>,
Heiner Kallweit <hkallweit1@gmail.com>
Subject: Re: [PATCH] usbnet: Fix use-after-free on disconnect
Date: Thu, 14 Apr 2022 12:58:58 +0200 [thread overview]
Message-ID: <20220414105858.GA9106@wunner.de> (raw)
In-Reply-To: <614e6498-3c3e-0104-591e-8ea296dfd887@suse.com>
On Wed, Apr 13, 2022 at 08:59:48PM +0200, Oliver Neukum wrote:
> On 13.04.22 16:16, Lukas Wunner wrote:
> > Jann Horn reports a use-after-free on disconnect of a USB Ethernet
> > (ax88179_178a.c). Oleksij Rempel has witnessed the same issue with a
> > different driver (ax88172a.c).
>
> I see. Very good catch
>
> > --- a/drivers/net/usb/usbnet.c
> > +++ b/drivers/net/usb/usbnet.c
> > @@ -469,6 +469,9 @@ static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
> > */
> > void usbnet_defer_kevent (struct usbnet *dev, int work)
> > {
> > + if (dev->intf->condition == USB_INTERFACE_UNBINDING)
> > + return;
>
> But, no, you cannot do this. This is a very blatant layering violation.
> You cannot use states internal to usb core like that in a driver.
Why do you think it's internal?
enum usb_interface_condition is defined in include/linux/usb.h
for everyone to see and use. If it was meant to be private,
I'd expect it to be marked as such or live in drivers/usb/core/usb.h.
Adding Greg to clarify.
> I see two options.
> 1. A dedicated flag in usbnet (then please with the correct smp barriers)
> 2. You introduce an API to usb core to query this.
I'd definitely prefer option 2 as I'd hate to duplicate functionality.
What do you have in mind? A simple accessor to return intf->condition
or something like usb_interface_unbinding() which returns a bool?
Thanks,
Lukas
next prev parent reply other threads:[~2022-04-14 10:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 14:16 [PATCH] usbnet: Fix use-after-free on disconnect Lukas Wunner
2022-04-13 18:59 ` Oliver Neukum
2022-04-14 10:58 ` Lukas Wunner [this message]
2022-04-14 11:07 ` Greg Kroah-Hartman
2022-04-17 7:28 ` Lukas Wunner
2022-04-14 11:20 ` Oliver Neukum
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