On Tue, Jun 26, 2018 at 8:56 PM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> The vt code translates UTF-8 strings into glyph index values and stores
> those glyph values directly in the screen buffer. Because there can only
> be at most 512 glyphs, it is impossible to represent most unicode
> characters, in which case a default glyph (often '?') is displayed
> instead. The original unicode value is then lost.
>
> This patch implements the basic screen buffer handling to preserve unicode
> values alongside corresponding display glyphs. It is not activated by
> default, meaning that people not relying on that functionality won't get
> the implied overhead.
>
> Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxx>
> Tested-by: Dave Mielke <Dave@xxxxxxxxx>
> Acked-by: Adam Borowski <kilobyte@xxxxxxxxxx>
> ---
> drivers/tty/vt/vt.c | 220 +++++++++++++++++++++++++++++++--
> include/linux/console_struct.h | 2 +
> 2 files changed, 211 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index 1eb1a376a0..7b636638b3 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> [...]
> +static void vc_uniscr_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
> + enum con_scroll dir, unsigned int nr)
> +{
> + struct uni_screen *uniscr = get_vc_uniscr(vc);
> +
> + if (uniscr) {
> + unsigned int s, d, rescue, clear;
> + char32_t *save[nr];
Can you adjust this to avoid the VLA here? I've almost gotten all VLAs
removed from the kernel[1], and this is introducing a new one. :)
Thanks!
-Kees
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@xxxxxxxxxxxxxx
> +
> + s = clear = t;
> + d = t + nr;
> + rescue = b - nr;
> + if (dir == SM_UP) {
> + swap(s, d);
> + swap(clear, rescue);
> + }
> + memcpy(save, uniscr->lines + rescue, nr * sizeof(*save));
> + memmove(uniscr->lines + d, uniscr->lines + s,
> + (b - t - nr) * sizeof(*uniscr->lines));
> + memcpy(uniscr->lines + clear, save, nr * sizeof(*save));
> + vc_uniscr_clear_lines(vc, clear, nr);
> + }
> +}
--
Kees Cook
Pixel Security
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