From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D32F82F5E; Wed, 2 Jul 2025 01:26:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751419580; cv=none; b=FUeUTOv3PHN+hLghSktKMhgVTUQ31XimouaVo6mg4dYz3ehQYLkYptMa15KHm8vc/nJO4zC3X657NoDAIgZxHSr6TkWXIlbpIqblO01QDZhs6UTcl0WNe1obEMl4hVrZ9YTKFOPeshbVptuvSz5bSQKjPyNI/6s16aXlxdoVbUo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751419580; c=relaxed/simple; bh=kpNeMrG3Dt4hd8A0for0V8nnG/pC3jvPKfmzTIld6sQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=UunxqCgobFGG7gavkiltuLXJ/XgbGeXluLVCGftdZCDiBv6slrow1SGkiZLVKAcYVAVcz/vu+I1Woxb/pX/xviTcRzvZeFghngRt4yK5qbtISLwdMmag5/8cDAvZBZ7KkSqtkrPOWu05wgBvq8KY9NRRwmhzHkp756P3EWXCbto= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JAFl5gD1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JAFl5gD1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20D41C4CEEB; Wed, 2 Jul 2025 01:26:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751419578; bh=kpNeMrG3Dt4hd8A0for0V8nnG/pC3jvPKfmzTIld6sQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JAFl5gD1wB3U8t6EiLCi29YJ/X5QLu0Z63y6SqPAmuc/N2fMiP16+u7BL47rUV4Rp vAlrSI6DVvVoOCceeh1E4Be/ZN5Br36iRp+779w22nlcJglSBB7RDOxPZ1fwGsv/iN Vkoo7bjUwPWrxSmym682JDot3LKIiYXIYzXNgtq++Mq1EtGC7uQgSgIsiJB8mUa+Og LLXcj2Xn8YETjw6lJN035doe3udvvTukOV12jWnyOvj00q73roMS0NSv2lgYoAVR5y t2ov+K555lNCDDStMC5g6BO/C8ke7Lm5Vqc0YjCvUUDIFldczSu2Bb1oScjO7DamBv WkFe5wl7tiNXw== Date: Tue, 1 Jul 2025 18:26:17 -0700 From: Jakub Kicinski To: Oliver Neukum Cc: Paolo Abeni , "Peter GJ. Park" , Andrew Lunn , "David S. Miller" , Eric Dumazet , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: usb: usbnet: fix use-after-free in race on workqueue Message-ID: <20250701182617.07d6e437@kernel.org> In-Reply-To: References: <20250625-usbnet-uaf-fix-v1-1-421eb05ae6ea@samsung.com> <87a7f8a6-71b1-4b90-abc7-0a680f2a99cf@redhat.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 1 Jul 2025 15:22:54 +0200 Oliver Neukum wrote: > On 26.06.25 11:21, Paolo Abeni wrote: > >> drivers/net/usb/usbnet.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c > >> index c04e715a4c2ade3bc5587b0df71643a25cf88c55..3c5d9ba7fa6660273137c80106746103f84f5a37 100644 > >> --- a/drivers/net/usb/usbnet.c > >> +++ b/drivers/net/usb/usbnet.c > >> @@ -1660,6 +1660,9 @@ void usbnet_disconnect (struct usb_interface *intf) > >> usb_free_urb(dev->interrupt); > >> kfree(dev->padding_pkt); > >> > >> + timer_delete_sync(&dev->delay); > >> + tasklet_kill(&dev->bh); > >> + cancel_work_sync(&dev->kevent); > >> free_netdev(net); > > This happens after unregister_netdev(), which calls usbnet_stop() that > > already performs the above cleanup. How the race is supposed to take place? > > That is indeed a core question, which we really need an answer to. > Do I interpret dev_close_many() correctly, if I state that the > ndo_stop() method will _not_ be called if the device has never been > opened? Correct, open and close are paired. Most drivers would crash if we tried to close them before they ever got opened. > I am sorry to be a stickler here, but if that turns out to be true, > usbnet is not the only driver that has this bug. Shooting from the hip slightly, but its unusual for a driver to start link monitoring before open. After all there can be no packets on a device that's closed. Why not something like: diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 9564478a79cc..b75b0b5c3abc 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -896,6 +896,9 @@ int usbnet_open (struct net_device *net) int retval; const struct driver_info *info = dev->driver_info; + if (dev->driver_info->flags & FLAG_LINK_INTR) + usbnet_link_change(dev, 0, 0); + if ((retval = usb_autopm_get_interface(dev->intf)) < 0) { netif_info(dev, ifup, dev->net, "resumption fail (%d) usbnet usb-%s-%s, %s\n", @@ -1862,8 +1865,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) netif_device_attach (net); - if (dev->driver_info->flags & FLAG_LINK_INTR) - usbnet_link_change(dev, 0, 0); + netif_carrier_off(net); return 0;