Re: [PATCH 1/5] fbcon: Disallow setting font bigger than screen size
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2022-06-30 18:51:43
Also in:
dri-devel
Hi Helge, On Wed, Jun 29, 2022 at 10:00 PM Helge Deller [off-list ref] wrote:
Prevent that users set a font size which is bigger than the physical screen. It's unlikely this may happen (because screens are usually much larger than the fonts and each font char is limited to 32x32 pixels), but it may happen on smaller screens/LCD displays. Signed-off-by: Helge Deller <deller@gmx.de> Reviewed-by: Daniel Vetter <redacted>
Thanks for your patch! Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
quoted hunk ↗ jump to hunk
--- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c@@ -2469,6 +2469,11 @@ static int fbcon_set_font(struct vc_data *vc, struct console_font *font, if (charcount != 256 && charcount != 512) return -EINVAL; + /* font bigger than screen resolution ? */ + if (font->width > FBCON_SWAP(info->var.rotate, info->var.xres, info->var.yres) || + font->height > FBCON_SWAP(info->var.rotate, info->var.yres, info->var.xres))
Note that we already have local vars w and h, albeit with the wrong signedness.
+ return -EINVAL;
+
/* Make sure drawing engine can handle the font */
if (!(info->pixmap.blit_x & (1 << (font->width - 1))) ||
!(info->pixmap.blit_y & (1 << (font->height - 1))))
There were already more opportunities for using w and h before...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds