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

[Helge Deller <deller@gmx.de>]

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@vger.kernel.org
>> Signed-off-by: CatMe0w <CatMe0w@live.cn>
> 
> This patch restores fbcon on my test system with sisfb.
> 
> Tested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
> Closes: https://lore.kernel.org/linux-fbdev/b8b52ffd-ecec-4fba-b432-ba32135c2f99@suse.de/
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@live.cn>
Can you please sign off again with your real name?

Thanks!
Helge