linux-kernel - Re: [PATCH v2] b43legacy: Add checking for null for ssb_get

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Message-ID: <20230418181204.473e7898@barney>
Date:   Tue, 18 Apr 2023 18:12:04 +0200
From:   Michael Büsch <m@...s.ch>
To:     Nikita Zhandarovich <n.zhandarovich@...tech.ru>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        "John W. Linville" <linville@...driver.com>,
        <linux-wireless@...r.kernel.org>, <b43-dev@...ts.infradead.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <lvc-project@...uxtesting.org>,
        Natalia Petrova <n.petrova@...tech.ru>
Subject: Re: [PATCH v2] b43legacy: Add checking for null for
 ssb_get_devtypedata(dev)

On Tue, 18 Apr 2023 07:29:18 -0700
Nikita Zhandarovich <n.zhandarovich@...tech.ru> wrote:

> Since second call of ssb_get_devtypedata() may fail as well as the
> first one, the NULL return value in 'wl' will be later dereferenced in
> calls to b43legacy_one_core_attach() and schedule_work().

No, the second call can't fail, because b43legacy_wireless_init() will
always initialize it before returning 0.

> a/drivers/net/wireless/broadcom/b43legacy/main.c +++
> b/drivers/net/wireless/broadcom/b43legacy/main.c @@ -3857,7 +3857,11
> @@ static int b43legacy_probe(struct ssb_device *dev, if (err)
>  			goto out;
>  		wl = ssb_get_devtypedata(dev);
> -		B43legacy_WARN_ON(!wl);
> +		if (!wl) {
> +			B43legacy_WARN_ON(!wl);
> +			err = -ENODEV;
> +			goto out;

And the 'goto out' would be the wrong error recovery path, too.

> +		}
>  	}
>  	err = b43legacy_one_core_attach(dev, wl);
>  	if (err)


Nack.
Please drop this patch. The code is correct as-is.

-- 
Michael Büsch
https://bues.ch/

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