Re: [PATCH v2 04/16] b43: Remove uninitialized_var() usage

[Nick Desaulniers <ndesaulniers@xxxxxxxxxx>]

On Fri, Jun 19, 2020 at 8:30 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> 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.
> No later NULL deref is possible due to the early returns outside of the
> (phy->rev >= 7 && phy->rev < 19) case, which explicitly tests for NULL.
>
> [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@xxxxxxxxxx/
> [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@xxxxxxxxxxxxxx/
> [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@xxxxxxxxxxxxxx/
> [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@xxxxxxxxxxxxxx/
>
> Fixes: 58619b14d106 ("b43: move under broadcom vendor directory")
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

I see three total uses of uninitialized_var() in this file, do we want
to eliminate all of them?

> ---
>  drivers/net/wireless/broadcom/b43/phy_n.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/broadcom/b43/phy_n.c b/drivers/net/wireless/broadcom/b43/phy_n.c
> index c33b4235839d..46db91846007 100644
> --- a/drivers/net/wireless/broadcom/b43/phy_n.c
> +++ b/drivers/net/wireless/broadcom/b43/phy_n.c
> @@ -4222,7 +4222,7 @@ static void b43_nphy_tx_gain_table_upload(struct b43_wldev *dev)
>         u32 rfpwr_offset;
>         u8 pga_gain, pad_gain;
>         int i;
> -       const s16 *uninitialized_var(rf_pwr_offset_table);
> +       const s16 *rf_pwr_offset_table = NULL;
>
>         table = b43_nphy_get_tx_gain_table(dev);
>         if (!table)
> --

-- 
Thanks,
~Nick Desaulniers