Re: [alsa-devel] [PATCH] ASoC: fsl_spdif: Use 64-bit arithmetic instead of 32-bit

[Nicolin Chen]

On Wed, Jul 04, 2018 at 09:18:33AM -0500, Gustavo A. R. Silva wrote:
> Add suffix ULL to constant 64 in order to give the compiler complete
> information about the proper arithmetic to use.
> 
> Notice that such constant is used in a context that expects an
> expression of type u64 (64 bits, unsigned) and the following
> expression is currently being evaluated using 32-bit arithmetic:
> 
> rate[index] * txclk_df * 64
> 
> Addresses-Coverity-ID: 1222129 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>

Acked-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx>

Thanks.

> ---
>  sound/soc/fsl/fsl_spdif.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/fsl/fsl_spdif.c b/sound/soc/fsl/fsl_spdif.c
> index 9b59d87..740b90d 100644
> --- a/sound/soc/fsl/fsl_spdif.c
> +++ b/sound/soc/fsl/fsl_spdif.c
> @@ -1118,7 +1118,7 @@ static u32 fsl_spdif_txclk_caldiv(struct fsl_spdif_priv *spdif_priv,
>  
>  	for (sysclk_df = sysclk_dfmin; sysclk_df <= sysclk_dfmax; sysclk_df++) {
>  		for (txclk_df = 1; txclk_df <= 128; txclk_df++) {
> -			rate_ideal = rate[index] * txclk_df * 64;
> +			rate_ideal = rate[index] * txclk_df * 64ULL;
>  			if (round)
>  				rate_actual = clk_round_rate(clk, rate_ideal);
>  			else
> -- 
> 2.7.4
> 
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