Re: [PATCH] Fix NR_KEYS off-by-one error

Vojtech Pavlik
2004-07-16T16:44:16Z

On Sat, Jul 17, 2004 at 01:35:59AM +0900, OGAWA Hirofumi wrote:
> KDGKBENT ioctl can use 256 entries (0-255), but it was defined as
> key_map[NR_KEYS] (NR_KEYS == 255). The code seems also thinking it's 256.
>
> key_map[0] = U(K_ALLOCATED);
> for (j = 1; j < NR_KEYS; j++)
> key_map[j] = U(K_HOLE);

The patch below might cause problems, though, because some apps may (in
old versions are) using a char variable to index up to NR_KEYS, which
leads to an endless loop.

>
> Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
> ---
>
> include/linux/keyboard.h | 2 +-
> 1 files changed, 1 insertion(+), 1 deletion(-)
>
> diff -puN include/linux/keyboard.h~nr_keys-off-by-one include/linux/keyboard.h
> --- linux-2.6.8-rc1/include/linux/keyboard.h~nr_keys-off-by-one 2004-07-16 06:20:10.000000000 +0900
> +++ linux-2.6.8-rc1-hirofumi/include/linux/keyboard.h 2004-07-16 06:20:10.000000000 +0900
> @@ -16,7 +16,7 @@
>
> #define NR_SHIFT 9
>
> -#define NR_KEYS 255
> +#define NR_KEYS 256
> #define MAX_NR_KEYMAPS 256
> /* This means 128Kb if all keymaps are allocated. Only the superuser
> may increase the number of keymaps beyond MAX_NR_OF_USER_KEYMAPS. */
> _
>

--
Vojtech Pavlik
SuSE Labs, SuSE CR