Re: [PATCH 1/3] Input: xpad - add safer data access framework

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Processing GIP_CMD_ANNOUNCE can trigger sleeping functions from an URB completion handler.
--

--- Patch [1]: [PATCH 1/3] Input: xpad - add safer data access framework ---
commit 852b38f29eb8d0217357629e77fd629842b2aed4
Author: Griffin Kroah-Hartman <[email protected]>

Input: xpad - add safer data access framework

This commit introduces a safe_data struct and a safe data check function to
prevent reads and writes outside of the data buffer bounds.

> diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
> index feb8f368f834e..c516860711a82 100644
> --- a/drivers/input/joystick/xpad.c
> +++ b/drivers/input/joystick/xpad.c

[ ... ]

> @@ -1078,44 +1100,49 @@ static void xpadone_process_packet(struct usb_xpad *xpad, u16 cmd, unsigned char
[ ... ]
> -	} else if (data[0] == GIP_CMD_ANNOUNCE) {
> +	} else if (sdata_check(&sdata, 0) == GIP_CMD_ANNOUNCE) {
>  		int error;
>  
>  		if (xpad->delay_init && !xpad->delayed_init_done) {
>  			xpad->delayed_init_done = true;
>  			error = xpad_start_input(xpad);

[Severity: High]
This is a pre-existing issue, but does this code path trigger sleeping
functions from an atomic context?

When an Xbox One controller sends a GIP_CMD_ANNOUNCE packet on the irq_in
endpoint, the URB completion handler (which runs in atomic softirq context)
processes it via xpadone_process_packet().

If xpad->delay_init is true and initialization hasn't completed, it calls
xpad_start_input(), which subsequently uses GFP_KERNEL:

xpad_start_input() {
    ...
    if (usb_submit_urb(xpad->irq_in, GFP_KERNEL))
        return -EIO;
    ...
}

Additionally, xpad_start_input() calls xpad_start_xbox_one(), which makes a
synchronous blocking call that sleeps:

xpad_start_xbox_one() {
    ...
    error = usb_set_interface(xpad->udev, GIP_WIRED_INTF_AUDIO, 0);
    ...
}

Could this lead to a scheduling while atomic kernel panic when a device sends
this command during URB completion?

>  			if (error)
>  				dev_warn(&xpad->dev->dev,
>  					 "unable to start delayed input: %d\n",
>  					 error);
>  		}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1