Re: [PATCH v2] b43legacy: Add checking for null for ssb_get_devtypedata(dev)

From: Larry Finger <Larry.Finger@lwfinger.net>
To: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Cc: Kalle Valo <kvalo@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	"John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	lvc-project@linuxtesting.org,
	Natalia Petrova <n.petrova@fintech.ru>
Subject: Re: [PATCH v2] b43legacy: Add checking for null for ssb_get_devtypedata(dev)
Date: Fri, 21 Apr 2023 17:14:18 -0500	[thread overview]
Message-ID: <95cff855-cb12-cf66-888f-b296a712d37d@lwfinger.net> (raw)
In-Reply-To: <20230418142918.70510-1-n.zhandarovich@fintech.ru>

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@fintech.ru>
> Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
> ---
> v2: fix issues with overlooked null-ptr-dereferences pointed out by
> Simon Horman <simon.horman@corigine.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@lwfinger.net>

Thanks,

Larry

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