netdev - Re: [PATCH] drivers: net: wireless: ath: ath9k: dfs: remove VLA usage

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Message-ID: <1520602169.26370.1.camel@perches.com>
Date:   Fri, 09 Mar 2018 05:29:29 -0800
From:   Joe Perches <joe@...ches.com>
To:     Andreas Christoforou <andreaschristofo@...il.com>,
        keescook@...omium.org
Cc:     kernel-hardening@...ts.openwall.com,
        QCA ath9k Development <ath9k-devel@....qualcomm.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: net: wireless: ath: ath9k: dfs: remove VLA
 usage

On Fri, 2018-03-09 at 15:23 +0200, Andreas Christoforou wrote:
> The kernel would like to have all stack VLA usage removed.
> This is the correct patch.
[]
> diff --git a/drivers/net/wireless/ath/ath9k/dfs.c b/drivers/net/wireless/ath/ath9k/dfs.c
[]
> @@ -101,7 +101,7 @@ static bool ath9k_check_chirping(struct ath_softc *sc, u8 *data,
>  				 int datalen, bool is_ctl, bool is_ext)
>  {
>  	int i;
> -	int max_bin[FFT_NUM_SAMPLES];
> +	int max_bin[NUM_DIFFS + 1];
>  	struct ath_hw *ah = sc->sc_ah;
>  	struct ath_common *common = ath9k_hw_common(ah);
>  	int prev_delta;

why not just change FFT_NUM_SAMPLES to a #define
or get rid if FFT_NUM_SAMPLES altogether?

$ git grep -w FFT_NUM_SAMPLES
drivers/net/wireless/ath/ath9k/dfs.c:static const int FFT_NUM_SAMPLES   = (NUM_DIFFS + 1);
drivers/net/wireless/ath/ath9k/dfs.c:   int max_bin[FFT_NUM_SAMPLES];
drivers/net/wireless/ath/ath9k/dfs.c:           if (num_fft_packets < (FFT_NUM_SAMPLES)) {
drivers/net/wireless/ath/ath9k/dfs.c:           for (i = 0; i < FFT_NUM_SAMPLES; i++)
drivers/net/wireless/ath/ath9k/dfs.c:           if (num_fft_packets < (FFT_NUM_SAMPLES)) {
drivers/net/wireless/ath/ath9k/dfs.c:           for (i = 0; i < FFT_NUM_SAMPLES; i++)