Re: [PATCH] Input: gf2k: clamp hat values to the lookup table

[Dmitry Torokhov]

On Mon, Mar 23, 2026 at 03:45:41PM +0800, Pengpeng Hou wrote:
> gf2k_read() decodes the hat position from a 4-bit field and uses it
> directly to index gf2k_hat_to_axis[]. The lookup table only has nine
> entries, so malformed packets can read past the end of the fixed table.
> 
> Clamp invalid hat values to the neutral position before indexing the
> lookup table.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@xxxxxxxxxxx>
> ---
>  drivers/input/joystick/gf2k.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/input/joystick/gf2k.c b/drivers/input/joystick/gf2k.c
> index 5a1cdce0bc48..78fba36285dc 100644
> --- a/drivers/input/joystick/gf2k.c
> +++ b/drivers/input/joystick/gf2k.c
> @@ -164,6 +164,8 @@ static void gf2k_read(struct gf2k *gf2k, unsigned char *data)
>  		input_report_abs(dev, gf2k_abs[i], GB(i*9+60,8,0) | GB(i+54,1,9));
>  
>  	t = GB(40,4,0);
> +	if (t >= ARRAY_SIZE(gf2k_hat_to_axis))
> +		t = 0;

I think if "t" is too bug we should skip the loop instead of reporting
the first axis.

>  
>  	for (i = 0; i < gf2k_hats[gf2k->id]; i++)
>  		input_report_abs(dev, ABS_HAT0X + i, gf2k_hat_to_axis[t][i]);

Thanks.

-- 
Dmitry