Hi Tigran,
On Thu, 27 Mar 2025 at 16:13, Tigran Sogomonian
<tsogomonian@xxxxxxxxxxxxx> wrote:
> To avoid division by zero, a check was added to the prate
> variable, since no guarantees were found that it could not
> be equal to zero.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Signed-off-by: Tigran Sogomonian <tsogomonian@xxxxxxxxxxxxx>
Thanks for your patch!
> --- a/drivers/clk/renesas/rcar-gen3-cpg.c
> +++ b/drivers/clk/renesas/rcar-gen3-cpg.c
> @@ -205,6 +205,8 @@ static int cpg_z_clk_determine_rate(struct clk_hw *hw,
> prate * zclk->fixed_div);
>
> prate = req->best_parent_rate / zclk->fixed_div;
> + if (prate == 0)
> + return -EINVAL;
prate can never be zero, as req->best_parent_rate is always larger or
equal than zclk->max_rate, and zclk->fixed_div is a very small number
(2 or 4).
> min_mult = max(div64_ul(req->min_rate * 32ULL, prate), 1ULL);
> max_mult = min(div64_ul(req->max_rate * 32ULL, prate), 32ULL);
> if (max_mult < min_mult)
> diff --git a/drivers/clk/renesas/rcar-gen4-cpg.c b/drivers/clk/renesas/rcar-gen4-cpg.c
> index 31aa790fd003..4c9a7d699290 100644
> --- a/drivers/clk/renesas/rcar-gen4-cpg.c
> +++ b/drivers/clk/renesas/rcar-gen4-cpg.c
> @@ -308,6 +308,8 @@ static int cpg_z_clk_determine_rate(struct clk_hw *hw,
> prate * zclk->fixed_div);
>
> prate = req->best_parent_rate / zclk->fixed_div;
> + if (prate == 0)
> + return -EINVAL;
Likewise.
> min_mult = max(div64_ul(req->min_rate * 32ULL, prate), 1ULL);
> max_mult = min(div64_ul(req->max_rate * 32ULL, prate), 32ULL);
> if (max_mult < min_mult)
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
