[PATCH v2] fbconsole: check cursor position before moving

[Sascha Hauer]

On Fri, Feb 24, 2017 at 02:36:27PM +0100, Bastian Stender wrote:
> Moving the cursor to x=2, y=2 with "\e[3;3H" on a 12x2 framebuffer
> console lead to a barebox crash while drawing the cursor. If the
> cursor position is out of bounds clip the cursor to the corresponding
> edge.
> 
> Signed-off-by: Bastian Stender <bst at pengutronix.de>
> ---
>  drivers/video/fbconsole.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/video/fbconsole.c b/drivers/video/fbconsole.c
> index 64f7d7364e..843a026ff6 100644
> --- a/drivers/video/fbconsole.c
> +++ b/drivers/video/fbconsole.c
> @@ -264,10 +264,13 @@ static void fbc_parse_csi(struct fbc_priv *priv)
>  		return;
>  	case 'H':
>  		video_invertchar(priv, priv->x, priv->y);
> +
>  		pos = simple_strtoul(priv->csi, &end, 10);
> -		priv->y = pos ? pos - 1 : 0;
> +		priv->y = !pos ? 0 : pos < priv->rows ? pos - 1 : priv->rows - 1;
> +
>  		pos = simple_strtoul(end + 1, NULL, 10);
> -		priv->x = pos ? pos - 1 : 0;
> +		priv->x = !pos ? 0 : pos < priv->cols ? pos - 1 : priv->cols - 1;

Not nice to read. Fortunately this situation is common enough so that we
have a function for it:

		priv->x = clamp(pos, 0, priv->cols - 1);

Sascha

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