Re: [PATCH] PM: domains: fix overflow in genpd_parse_state

[Rafael J. Wysocki]

On Tue, May 30, 2023 at 1:42 PM YiMing Tseng <yimingtseng@xxxxxxxxxx> wrote:
>
> Add type casters to prevent 32-bit overflow before assigning to s64
> variables. It allows full 32-bit range support for latency and
> residency.

OK, but is it really a practical problem?

Ulf, what do you think?

> Signed-off-by: YiMing Tseng <yimingtseng@xxxxxxxxxx>
> ---
>  drivers/base/power/domain.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 32084e38b73d..26a04cd8d8dc 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2939,10 +2939,10 @@ static int genpd_parse_state(struct genpd_power_state *genpd_state,
>
>         err = of_property_read_u32(state_node, "min-residency-us", &residency);
>         if (!err)
> -               genpd_state->residency_ns = 1000 * residency;
> +               genpd_state->residency_ns = (s64)1000 * residency;
>
> -       genpd_state->power_on_latency_ns = 1000 * exit_latency;
> -       genpd_state->power_off_latency_ns = 1000 * entry_latency;
> +       genpd_state->power_on_latency_ns = (s64)1000 * exit_latency;
> +       genpd_state->power_off_latency_ns = (s64)1000 * entry_latency;
>         genpd_state->fwnode = &state_node->fwnode;
>
>         return 0;
> --