linux-kernel - Re: [PATCH] ar5523: check endpoints type and direction in probe()

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Date:   Wed, 24 Aug 2022 08:04:35 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Mazin Al Haddad <mazinalhaddad05@...il.com>
Cc:     pontus.fuchs@...il.com, netdev@...r.kernel.org, kvalo@...nel.org,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzbot+1bc2c2afd44f820a669f@...kaller.appspotmail.com,
        edumazet@...gle.com, paskripkin@...il.com, kuba@...nel.org,
        pabeni@...hat.com, linux-kernel-mentees@...ts.linuxfoundation.org,
        davem@...emloft.net
Subject: Re: [PATCH] ar5523: check endpoints type and direction in probe()

On Wed, Aug 24, 2022 at 01:24:38AM +0300, Mazin Al Haddad wrote:
> Fixes a bug reported by syzbot, where a warning occurs in usb_submit_urb()
> due to the wrong endpoint type. There is no check for both the number
> of endpoints and the type which causes an error as the code tries to
> send a URB to the wrong endpoint.
> 
> Fix it by adding a check for the number of endpoints and the
> direction/type of the endpoints. If the endpoints do not match the 
> expected configuration -ENODEV is returned.
> 
> Syzkaller report:
> 
> usb 1-1: BOGUS urb xfer, pipe 3 != type 1
> WARNING: CPU: 1 PID: 71 at drivers/usb/core/urb.c:502 usb_submit_urb+0xed2/0x18a0 drivers/usb/core/urb.c:502
> Modules linked in:
> CPU: 1 PID: 71 Comm: kworker/1:2 Not tainted 5.19.0-rc7-syzkaller-00150-g32f02a211b0a #0
> Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
> Workqueue: usb_hub_wq hub_event
> Call Trace:
>  <TASK>
>  ar5523_cmd+0x420/0x790 drivers/net/wireless/ath/ar5523/ar5523.c:275
>  ar5523_cmd_read drivers/net/wireless/ath/ar5523/ar5523.c:302 [inline]
>  ar5523_host_available drivers/net/wireless/ath/ar5523/ar5523.c:1376 [inline]
>  ar5523_probe+0xc66/0x1da0 drivers/net/wireless/ath/ar5523/ar5523.c:1655
> 
> 
> Link: https://syzkaller.appspot.com/bug?extid=1bc2c2afd44f820a669f
> Reported-and-tested-by: syzbot+1bc2c2afd44f820a669f@...kaller.appspotmail.com
> Signed-off-by: Mazin Al Haddad <mazinalhaddad05@...il.com>
> ---
>  drivers/net/wireless/ath/ar5523/ar5523.c | 31 ++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
> index 6f937d2cc126..5451bf9ab9fb 100644
> --- a/drivers/net/wireless/ath/ar5523/ar5523.c
> +++ b/drivers/net/wireless/ath/ar5523/ar5523.c
> @@ -1581,8 +1581,39 @@ static int ar5523_probe(struct usb_interface *intf,
>  	struct usb_device *dev = interface_to_usbdev(intf);
>  	struct ieee80211_hw *hw;
>  	struct ar5523 *ar;
> +	struct usb_host_interface *host = intf->cur_altsetting;
>  	int error = -ENOMEM;
>  
> +	if (host->desc.bNumEndpoints != 4) {
> +		dev_err(&dev->dev, "Wrong number of endpoints\n");
> +		return -ENODEV;
> +	}
> +
> +	for (int i = 0; i < host->desc.bNumEndpoints; ++i) {
> +		struct usb_endpoint_descriptor *ep = &host->endpoint[i].desc;
> +		// Check for type of endpoint and direction.
> +		switch (i) {
> +		case 0:
> +		case 1:
> +			if ((ep->bEndpointAddress & USB_DIR_OUT) &&
> +			    ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
> +			     == USB_ENDPOINT_XFER_BULK)){

Did you run your change through checkpatch?

> +				dev_err(&dev->dev, "Wrong type of endpoints\n");
> +				return -ENODEV;
> +			}
> +			break;
> +		case 2:
> +		case 3:
> +			if ((ep->bEndpointAddress & USB_DIR_IN) &&
> +			    ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
> +			     == USB_ENDPOINT_XFER_BULK)){
> +				dev_err(&dev->dev, "Wrong type of endpoints\n");
> +				return -ENODEV;
> +			}
> +			break;
> +		}

We have usb helper functions for all of this, why not use them instead
of attempting to roll your own?

thanks,

greg k-h