Re: [PATCH] fbdev: bitblit: Fix glyph clipping when fbcon pans

[Helge Deller]

On 10/20/26 13:40, Thomas Zimmermann wrote:
> Hi
>
> Am 17.10.26 um 10:53 schrieb CatMe0w:
> > Commit 3637d34b35b2 ("fbdev: Add bounds checking in bit_putcs to fix
> > vmalloc-out-of-bounds") made bit_putcs() clip glyphs to var.yres. When
> > fbcon scrolls by panning, it draws text rows up to var.yres_virtual,
> > so after the first pan most new text is not drawn until the next full
> > redraw. This affects fbdev drivers that set FBINFO_HWACCEL_YPAN or
> > FBINFO_HWACCEL_YWRAP, such as vesafb with the ypan option, when
> > CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION=y.
> >
> > Clip to GETVYRES() instead, which fbcon_ud.c and fbcon_ccw.c already
> > use as the drawing area height. When fbcon does not pan, GETVYRES()
> > returns var.yres, keeping the existing bound. When fbcon pans, it
> > returns var.yres_virtual, which the framebuffer memory must cover
> > anyway for panning to work.
> >
> > Fixes: 3637d34b35b2 ("fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: CatMe0w <CatMe0w@xxxxxxx>
>
> This patch restores fbcon on my test system with sisfb.
>
> Tested-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Reported-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Closes: https://lore.kernel.org/linux-fbdev/b8b52ffd-ecec-4fba-b432-ba32135c2f99@xxxxxxx/
Thomas, thanks for testing!

CatMe0w, I'd like to take your patch, but as Greg already pointed out,
I can't take anonymous contributions.
This "Signed-off-by" isn't valid:
Signed-off-by: CatMe0w <CatMe0w@xxxxxxx>
Can you please sign off again with your real name?

Thanks!
Helge