[Mesa-dev] [PATCH 3/4] gallium/hud: prevent an infinite loop

[Nicolai Hähnle]

On 20.02.2017 18:44, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
>
> ---
>  src/gallium/auxiliary/hud/hud_context.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/auxiliary/hud/hud_context.c b/src/gallium/auxiliary/hud/hud_context.c
> index aaa52d5..488fe66 100644
> --- a/src/gallium/auxiliary/hud/hud_context.c
> +++ b/src/gallium/auxiliary/hud/hud_context.c
> @@ -724,23 +724,23 @@ hud_pane_set_max_value(struct hud_pane *pane, uint64_t value)
>     uint64_t exp10;
>     int i;
>
>     /* The following code determines the max_value in the graph as well as
>      * how many describing lines are drawn. The max_value is rounded up,
>      * so that all drawn numbers are rounded for readability.
>      * We want to print multiples of a simple number instead of multiples of
>      * hard-to-read numbers like 1.753.
>      */
>
> -   /* Find the left-most digit. */
> +   /* Find the left-most digit. Make sure exp10 * 9 doesn't overflow. */
>     exp10 = 1;
> -   for (i = 0; value > 9 * exp10; i++) {
> +   for (i = 0; exp10 <= UINT64_MAX / 9 && exp10 * 9 < value; i++) {

Should this be UINT64_MAX / 10, so that the line below doesn't overflow?

>        exp10 *= 10;
>        fixup_bytes(pane->type, i + 1, &exp10);
>     }
>
>     leftmost_digit = DIV_ROUND_UP(value, exp10);
>
>     /* Round 9 to 10. */
>     if (leftmost_digit == 9) {
>        leftmost_digit = 1;
>        exp10 *= 10;
>