Re: [PATCH] wifi: carl9170: add a proper sanity check for endpoints

[Christian Lamparter]

On 4/7/24 3:11 PM, Nikita Zhandarovich wrote:
> Syzkaller reports [1] hitting a warning which is caused by presence
> of a wrong endpoint type at the URB sumbitting stage. While there
> was a check for a specific 4th endpoint, since it can switch types
> between bulk and interrupt, other endpoints are trusted implicitly.
> Similar warning is triggered in a couple of other syzbot issues [2].
>
> Fix the issue by doing a comprehensive check of all endpoints
> taking into account difference between high- and full-speed
> configuration.
>
> This patch has not been tested on real hardware.
>
> [1] Syzkaller report:
> ...
> WARNING: CPU: 0 PID: 4721 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504
> ...
> Call Trace:
>   <TASK>
>   carl9170_usb_send_rx_irq_urb+0x273/0x340 drivers/net/wireless/ath/carl9170/usb.c:504
>   carl9170_usb_init_device drivers/net/wireless/ath/carl9170/usb.c:939 [inline]
>   carl9170_usb_firmware_finish drivers/net/wireless/ath/carl9170/usb.c:999 [inline]
>   carl9170_usb_firmware_step2+0x175/0x240 drivers/net/wireless/ath/carl9170/usb.c:1028
>   request_firmware_work_func+0x130/0x240 drivers/base/firmware_loader/main.c:1107
>   process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289
>   worker_thread+0x669/0x1090 kernel/workqueue.c:2436
>   kthread+0x2e8/0x3a0 kernel/kthread.c:376
>   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
>   </TASK>
>
> [2] Related syzkaller crashes:
> Link: https://syzkaller.appspot.com/bug?extid=e394db78ae0b0032cb4d
> Link: https://syzkaller.appspot.com/bug?extid=9468df99cb63a4a4c4e1
>
> Reported-and-tested-by: syzbot+0ae4804973be759fa420@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: a84fab3cbfdc ("carl9170: 802.11 rx/tx processing and usb backend")
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>

This was tricky. USB 2.0 works and was easy to test.
But I had to hunt down a FULLSPEED USB Host for this.
The driver loads on with a OHCI Host (Silicon Image, Inc. USB0673 (rev 06))

So, I think this would work. But see my comments below.

> ---
> P.S. as AR9170_USB_EP_CMD endpoint can switch between bulk and int,
> I failed to find a prettier solution to this problem. Will be glad
> to hear if there is a better option...
>
>   drivers/net/wireless/ath/carl9170/usb.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/carl9170/usb.c b/drivers/net/wireless/ath/carl9170/usb.c
> index c4edf8355941..66d2ad561fd3 100644
> --- a/drivers/net/wireless/ath/carl9170/usb.c
> +++ b/drivers/net/wireless/ath/carl9170/usb.c
> @@ -1069,6 +1069,33 @@ static int carl9170_usb_probe(struct usb_interface *intf,
>   			ar->usb_ep_cmd_is_bulk = true;
>   	}
>   
> +	/* Verify that all expected endpoints are present */
> +	if (ar->usb_ep_cmd_is_bulk) {
> +		u8 bulk_ep_addr[] = {
> +			AR9170_USB_EP_RX | USB_DIR_IN,
> +			AR9170_USB_EP_TX | USB_DIR_OUT,
> +			AR9170_USB_EP_CMD | USB_DIR_OUT,
> +			0};
> +		u8 int_ep_addr[] = {
> +			AR9170_USB_EP_IRQ | USB_DIR_IN,
> +			0};
> +		if (!usb_check_bulk_endpoints(intf, bulk_ep_addr) ||
> +		    !usb_check_int_endpoints(intf, int_ep_addr))
> +			return -ENODEV;

Please call carl9170_free(ar); before returning here.
Otherwise the "ar" will memleak'ed.

> +	} else {
> +		u8 bulk_ep_addr[] = {
> +			AR9170_USB_EP_RX | USB_DIR_IN,
> +			AR9170_USB_EP_TX | USB_DIR_OUT,
> +			0};
> +		u8 int_ep_addr[] = {
> +			AR9170_USB_EP_IRQ | USB_DIR_IN,
> +			AR9170_USB_EP_CMD | USB_DIR_OUT,
> +			0};
> +		if (!usb_check_bulk_endpoints(intf, bulk_ep_addr) ||
> +		    !usb_check_int_endpoints(intf, int_ep_addr))
> +			return -ENODEV;

Same here.

> +	}
> +
>   	usb_set_intfdata(intf, ar);
>   	SET_IEEE80211_DEV(ar->hw, &intf->dev);
>