linux-kernel - Re: [PATCH v1 1/1] i2c: robotfuzz-osif: Propagate parent device to I2C core

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Message-ID: <YhNhxPEt6kZ2xzMJ@hovoldconsulting.com>
Date:   Mon, 21 Feb 2022 10:56:20 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wolfram Sang <wsa@...nel.org>,
        syzbot+0591ccf54ee05344e4eb@...kaller.appspotmail.com
Subject: Re: [PATCH v1 1/1] i2c: robotfuzz-osif: Propagate parent device to
 I2C core

On Fri, Feb 04, 2022 at 05:17:26PM +0200, Andy Shevchenko wrote:
> I2C core might use parent device to retrieve properties of
> the controller. Propagate parent device for that.

What is the problem you're trying to solve here?

If you've changed some core function so that the kernel crashes because
of this, you need to address this in core.

Looks like you're also changing the device topology with this change.

This needs more details.

> Fixes: 83e53a8f120f ("i2c: Add bus driver for for OSIF USB i2c device.")

This isn't the commit causing the NULL deref.

> Reported-by: syzbot+0591ccf54ee05344e4eb@...kaller.appspotmail.com
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/i2c/busses/i2c-robotfuzz-osif.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-robotfuzz-osif.c b/drivers/i2c/busses/i2c-robotfuzz-osif.c
> index 66dfa211e736..bfbfa0d07bb2 100644
> --- a/drivers/i2c/busses/i2c-robotfuzz-osif.c
> +++ b/drivers/i2c/busses/i2c-robotfuzz-osif.c
> @@ -128,6 +128,7 @@ MODULE_DEVICE_TABLE(usb, osif_table);
>  static int osif_probe(struct usb_interface *interface,
>  			     const struct usb_device_id *id)
>  {
> +	struct device *dev = &interface->dev;
>  	int ret;
>  	struct osif_priv *priv;
>  	u16 version;
> @@ -145,6 +146,7 @@ static int osif_probe(struct usb_interface *interface,
>  	priv->adapter.class = I2C_CLASS_HWMON;
>  	priv->adapter.algo = &osif_algorithm;
>  	priv->adapter.algo_data = priv;
> +	priv->adapter.dev.parent = dev;
>  	snprintf(priv->adapter.name, sizeof(priv->adapter.name),
>  		 "OSIF at bus %03d device %03d",
>  		 priv->usb_dev->bus->busnum, priv->usb_dev->devnum);

Johan