Re: [Qemu-devel] [PATCH 4/8] hw/arm/omap1: Avoid unintended sign extension writing omap_rtc YEARS_REG

[Peter Crosthwaite]

On Fri, May 9, 2014 at 4:46 AM, Peter Maydell <address@hidden> wrote:
> When writing to the YEARS_REG register, if the year value is
> 99 then the multiplication by 31536000 will overflow into
> the sign bit of a 32 bit value and then be erroneously
> sign-extended if time_t is 64 bits. Add a cast to avoid this.
>
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed-by: Peter Crosthwaite <address@hidden>

> ---
>  hw/arm/omap1.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/arm/omap1.c b/hw/arm/omap1.c
> index b433748..b28e052 100644
> --- a/hw/arm/omap1.c
> +++ b/hw/arm/omap1.c
> @@ -2709,8 +2709,8 @@ static void omap_rtc_write(void *opaque, hwaddr addr,
>              s->ti += ti[1];
>          } else {
>              /* A less accurate version */
> -            s->ti -= (s->current_tm.tm_year % 100) * 31536000;
> -            s->ti += from_bcd(value) * 31536000;
> +            s->ti -= (time_t)(s->current_tm.tm_year % 100) * 31536000;
> +            s->ti += (time_t)from_bcd(value) * 31536000;
>          }
>          return;
>
> --
> 1.9.2
>
>