font: Assign null_font to glyphs in ascii_font_glyph[]

The calculations in blit_comb() need information from glyph's font, e.g.
grub_font_get_xheight(main_glyph->font). However, main_glyph->font is
NULL if main_glyph comes from ascii_font_glyph[]. Therefore
grub_font_get_*() crashes because of NULL pointer.

There is already a solution, the null_font. So, assign it to those glyphs
in ascii_font_glyph[].

Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Zhang Boyang 2022-10-28 17:29:16 +08:00 committed by Daniel Kiper
parent 9d81f71c6b
commit 22b77b87e1

View File

@ -137,7 +137,7 @@ ascii_glyph_lookup (grub_uint32_t code)
ascii_font_glyph[current]->offset_x = 0;
ascii_font_glyph[current]->offset_y = -2;
ascii_font_glyph[current]->device_width = 8;
ascii_font_glyph[current]->font = NULL;
ascii_font_glyph[current]->font = &null_font;
grub_memcpy (ascii_font_glyph[current]->bitmap,
&ascii_bitmaps[current * ASCII_BITMAP_SIZE],