linux-kernel - Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from

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Message-ID: <20190810101316.GA25650@kroah.com>
Date:   Sat, 10 Aug 2019 12:13:16 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Hui Peng <benquike@...il.com>
Cc:     kvalo@...eaurora.org, davem@...emloft.net,
        Mathias Payer <mathias.payer@...elwelt.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in
 ath6kl_usb_alloc_urb_from_pipe

On Sat, Aug 03, 2019 at 08:29:04PM -0400, Hui Peng wrote:
> The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
> are initialized to point to the containing `ath6kl_usb` object
> according to endpoint descriptors read from the device side, as shown
> below in `ath6kl_usb_setup_pipe_resources`:
> 
> for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
> 	endpoint = &iface_desc->endpoint[i].desc;
> 
> 	// get the address from endpoint descriptor
> 	pipe_num = ath6kl_usb_get_logical_pipe_num(ar_usb,
> 						endpoint->bEndpointAddress,
> 						&urbcount);
> 	......
> 	// select the pipe object
> 	pipe = &ar_usb->pipes[pipe_num];
> 
> 	// initialize the ar_usb field
> 	pipe->ar_usb = ar_usb;
> }
> 
> The driver assumes that the addresses reported in endpoint
> descriptors from device side  to be complete. If a device is
> malicious and does not report complete addresses, it may trigger
> NULL-ptr-deref `ath6kl_usb_alloc_urb_from_pipe` and
> `ath6kl_usb_free_urb_to_pipe`.
> 
> This patch fixes the bug by preventing potential NULL-ptr-deref.
> 
> Signed-off-by: Hui Peng <benquike@...il.com>
> Reported-by: Hui Peng <benquike@...il.com>
> Reported-by: Mathias Payer <mathias.payer@...elwelt.net>

Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>