linux-kernel - Re: Highly critical bug in XHCI Controller

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Message-ID: <2024111731-neuter-customer-0230@gregkh>
Date: Sun, 17 Nov 2024 14:12:46 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Markus Rechberger <linuxusb.ml@...dtek.de>
Cc: linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Highly critical bug in XHCI Controller

On Sun, Nov 17, 2024 at 08:44:16PM +0800, Markus Rechberger wrote:
> Basically the issue comes from hub_port_connect.
> 
> drivers/usb/core/hub.c
> 
> hub_port_init returns -71 -EPROTO and jumps to loop
> https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L5450
> 
> I'd question if usb_ep0_reinit is really required in loop which is
> running following functions:
>     usb_disable_endpoint(udev, 0 + USB_DIR_IN, true);
>     usb_disable_endpoint(udev, 0 + USB_DIR_OUT, true);
>     usb_enable_endpoint(udev, &udev->ep0, true);
> 
> this is something only experience over the past decades can tell?
> 
> usb_enable_endpoint will trigger xhci_endpoint_reset which doesn't do
> much, but crashes the entire system with the upstream kernel when it
> triggers xhci_check_bw_table).
> 
> I removed usb_ep0_reinit here and devices are still workable under
> various conditions (again I shorted and pulled D+/D- to ground for
> testing).
> The NULL PTR check in xhci_check_bw_table would be a second line of
> defense but as indicated in the first mail it shouldn't even get there.
> 
> 
> 
> As a second issue I found in usb_reset_and_verify device 
> https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L6131
> 
>         ret = hub_port_init(parent_hub, udev, port1, i, &descriptor);
>         if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV) {
>             break;
>         }
> 
> hub_port_init can also return -71 / -EPROTO, the cases should be very
> rare when usb_reset_and_verify_device is triggered and that happens.
> 
> 
> I'm just waiting for comments now since this is some critical piece of
> infrastructure code before proceeding with a patch.

Send us a patch and we will be glad to review it.

thanks!

greg k-h