I am on vacation away from an actual keyboard until next week. Will look at it then.
> Le 10 juill. 2018 à 20:52, Kees Cook <keescook@xxxxxxxxxxxx> a écrit :
>
>> 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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