linux-kernel - Re: [PATCH 03/10] b43: Remove uninitialized

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Date:   Fri, 05 Jun 2020 12:20:55 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Joe Perches <joe@...ches.com>,
        Andy Whitcroft <apw@...onical.com>, x86@...nel.org,
        drbd-dev@...ts.linbit.com, linux-block@...r.kernel.org,
        b43-dev@...ts.infradead.org, netdev@...r.kernel.org,
        linux-wireless@...r.kernel.org, linux-ide@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-spi@...r.kernel.org,
        linux-mm@...ck.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH 03/10] b43: Remove uninitialized_var() usage

Kees Cook <keescook@...omium.org> writes:

> Using uninitialized_var() is dangerous as it papers over real bugs[1]
> (or can in the future), and suppresses unrelated compiler warnings (e.g.
> "unused variable"). If the compiler thinks it is uninitialized, either
> simply initialize the variable or make compiler changes. As a precursor
> to removing[2] this[3] macro[4], just initialize this variable to NULL,
> and make the (unreachable!) code do a conditional test.
>
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
>
> Signed-off-by: Kees Cook <keescook@...omium.org>

[...]

> @@ -4256,9 +4256,13 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
>  			pga_gain = (table[i] >> 24) & 0xf;
>  			pad_gain = (table[i] >> 19) & 0x1f;
>  			if (b43_current_band(dev->wl) == NL80211_BAND_2GHZ)
> -				rfpwr_offset = rf_pwr_offset_table[pad_gain];
> +				rfpwr_offset = rf_pwr_offset_table
> +						? rf_pwr_offset_table[pad_gain]
> +						: 0;
>  			else
> -				rfpwr_offset = rf_pwr_offset_table[pga_gain];
> +				rfpwr_offset = rf_pwr_offset_table
> +						? rf_pwr_offset_table[pga_gain]
> +						: 0;

To me this is ugly, isn't there a better way to fix this?

-- 
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