Re: [PATCH] Input: lpc32xx-keys - reject matrices bigger than the hardware has

[Dmitry Torokhov]

On Tue, Nov 03, 2026 at 04:41:32PM +0800, Guanglei Zhu wrote:
> The scanner state array holds the last state of eight matrix
> columns, and the interrupt handler walks the matrix size that the
> device tree declared:
> 
> 	u8 lastkeystates[8];
> 	...
> 	for (i = 0; i < kscandat->matrix_sz; i++)
> 		lpc32xx_mod_states(kscandat, i);
> 
> The probe path only checks that rows and columns match; the
> hardware supports square matrices from 1x1 up to 8x8, but nothing
> stops a device tree from declaring more, which makes the state
> array index run past the field into the rest of the driver data -
> including the keymap pointer the same code dereferences.
> 
> Reject matrices larger than the hardware supports.
> 
> Fixes: 69690bec400e ("Input: add support for key scan interface of the LPC32xx SoC")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guanglei Zhu <zhugl3@xxxxxxxxxxxx>
> ---
>  drivers/input/keyboard/lpc32xx-keys.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/input/keyboard/lpc32xx-keys.c b/drivers/input/keyboard/lpc32xx-keys.c
> index 285d5c32fe70..1d0b082e7881 100644
> --- a/drivers/input/keyboard/lpc32xx-keys.c
> +++ b/drivers/input/keyboard/lpc32xx-keys.c
> @@ -142,6 +142,11 @@ static int lpc32xx_parse_dt(struct device *dev,
>  		return -EINVAL;
>  	}
>  
> +	if (rows > 8) {

This should be a constant/#define.

> +		dev_err(dev, "rows and columns must be at most 8!\n");
> +		return -EINVAL;
> +	}
> +
>  	kscandat->matrix_sz = rows;
>  	kscandat->row_shift = get_count_order(columns);

Thanks.

-- 
Dmitry