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

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Message-ID: <95cff855-cb12-cf66-888f-b296a712d37d@lwfinger.net>
Date:   Fri, 21 Apr 2023 17:14:18 -0500
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Nikita Zhandarovich <n.zhandarovich@...tech.ru>
Cc:     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 4/18/23 09:29, Nikita Zhandarovich 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().
> 
> Instead of merely warning about this failure with
> B43legacy_WARN_ON(), properly return with error to avoid any further
> NULL pointer dereferences.
> 
> Found by Linux Verification Center (linuxtesting.org) with static
> analysis tool SVACE.
> 
> Fixes: 75388acd0cd8 ("[B43LEGACY]: add mac80211-based driver for legacy BCM43xx devices")
> Co-developed-by: Natalia Petrova <n.petrova@...tech.ru>
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
> ---
> v2: fix issues with overlooked null-ptr-dereferences pointed out by
> Simon Horman <simon.horman@...igine.com>
> Link: https://lore.kernel.org/all/Y+eb9mZntfe6rO3v@corigine.com/
> 
>   drivers/net/wireless/broadcom/b43legacy/main.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/broadcom/b43legacy/main.c b/drivers/net/wireless/broadcom/b43legacy/main.c
> index 760136638a95..5a706dd0b1a4 100644
> --- 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;
> +		}
>   	}
>   	err = b43legacy_one_core_attach(dev, wl);
>   	if (err)

I do not recall seeing v1. One additional nitpick: The latest convention would 
have the subject as "wifi: b43legacy:...". Kalle may be able to fix this on 
merging, but it not, a v3 might be required. Otherwise, the patch is good.

Reviewed-by: Larry Finger <Larry.Finger@...inger.net>

Thanks,

Larry