[PATCH] clk: imx: pll14xx: Fix potential integer overflow

[PATCH] clk: imx: pll14xx: Fix potential integer overflow

[Stefan Ghetu]

From: Florin Pavelescu <florin.pavelescu@nxp.com>

Cast to u64, so that multiplications and additions will be done
in 64-bit arithmetic (and the results will also be 64-bit)
and the possibility of integer overflow is eliminated.

Fixes: 53990cf9d5b48 ("clk: imx: pll14xx: consolidate rate calculation")
Signed-off-by: Florin Pavelescu <florin.pavelescu@nxp.com>
Signed-off-by: Stefan Ghetu <stefan.ghetu@nxp.com>
---
 drivers/clk/imx/clk-pll14xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/imx/clk-pll14xx.c b/drivers/clk/imx/clk-pll14xx.c
index c6438144e507..08f9d3fbc75f 100644
--- a/drivers/clk/imx/clk-pll14xx.c
+++ b/drivers/clk/imx/clk-pll14xx.c
@@ -124,7 +124,7 @@ static long pll14xx_calc_rate(struct clk_pll14xx *pll, int mdiv, int pdiv,
 	u64 fout = prate;
 
 	/* fout = (m * 65536 + k) * Fin / (p * 65536) / (1 << sdiv) */
-	fout *= (mdiv * 65536 + kdiv);
+	fout *= ((u64)mdiv * 65536 + (u64)kdiv);
 	pdiv *= 65536;
 
 	do_div(fout, pdiv << sdiv);
-- 
2.34.1

Re: [PATCH] clk: imx: pll14xx: Fix potential integer overflow

[Frank Li]

On Thu, Nov 05, 2026 at 11:46:32AM +0200, Stefan Ghetu wrote:
> [You don't often get email from stefan.ghetu@nxp.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> From: Florin Pavelescu <florin.pavelescu@nxp.com>
>
> Cast to u64, so that multiplications and additions will be done
> in 64-bit arithmetic (and the results will also be 64-bit)
> and the possibility of integer overflow is eliminated.
>
> Fixes: 53990cf9d5b48 ("clk: imx: pll14xx: consolidate rate calculation")
> Signed-off-by: Florin Pavelescu <florin.pavelescu@nxp.com>
> Signed-off-by: Stefan Ghetu <stefan.ghetu@nxp.com>
> ---
>  drivers/clk/imx/clk-pll14xx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clk/imx/clk-pll14xx.c b/drivers/clk/imx/clk-pll14xx.c
> index c6438144e507..08f9d3fbc75f 100644
> --- a/drivers/clk/imx/clk-pll14xx.c
> +++ b/drivers/clk/imx/clk-pll14xx.c
> @@ -124,7 +124,7 @@ static long pll14xx_calc_rate(struct clk_pll14xx *pll, int mdiv, int pdiv,
>         u64 fout = prate;
>
>         /* fout = (m * 65536 + k) * Fin / (p * 65536) / (1 << sdiv) */
> -       fout *= (mdiv * 65536 + kdiv);
> +       fout *= ((u64)mdiv * 65536 + (u64)kdiv);

suppose only need one cast.  u64 + u32 will convert u64 + u64 automatically.

Frank
>         pdiv *= 65536;
>
>         do_div(fout, pdiv << sdiv);
> --
> 2.34.1
>
>