Re: [PATCH] hw: cast 1 to 1ULL

[Richard Henderson]

On 12/26/24 01:58, Tigran Sogomonian wrote:
> To prevent integer overflow it is worth casting 1 to 1ULL.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Signed-off-by: Tigran Sogomonian <tsogomonian@astralinux.ru>
> ---
>   hw/misc/mps2-fpgaio.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/misc/mps2-fpgaio.c b/hw/misc/mps2-fpgaio.c
> index d07568248d..297cb1b602 100644
> --- a/hw/misc/mps2-fpgaio.c
> +++ b/hw/misc/mps2-fpgaio.c
> @@ -198,7 +198,7 @@ static void mps2_fpgaio_write(void *opaque, hwaddr offset, 
> uint64_t value,
>   
>               s->led0 = value & MAKE_64BIT_MASK(0, s->num_leds);
>               for (i = 0; i < s->num_leds; i++) {
> -                led_set_state(s->led[i], value & (1 << i));
> +                led_set_state(s->led[i], value & (1ULL << i));
>               }
>           }
>           break;

s->num_leds is bounded by MPS2FPGAIO_MAX_LEDS, which is 32.
There is no possible integer overflow here.

Please give more than a cursory look at the code.


r~