Re: Text mode VGA-console scrolling is broken in upstream & stable trees

[Salvatore Bonaccorso <carnil@debian.org>]

Hi,

On Wed, Jul 30, 2025 at 04:26:44PM +0200, Greg Kroah-Hartman wrote:
> On Wed, Jul 30, 2025 at 02:06:27PM +0000, Jari Ruusu wrote:
> > The patch that broke text mode VGA-console scrolling is this one:
> > "vgacon: Add check for vc_origin address range in vgacon_scroll()"
> > commit 864f9963ec6b4b76d104d595ba28110b87158003 upstream.
> > 
> > How to preproduce:
> > (1) boot a kernel that is configured to use text mode VGA-console
> > (2) type commands:  ls -l /usr/bin | less -S
> > (3) scroll up/down with cursor-down/up keys
> > 
> > Above mentioned patch seems to have landed in upstream and all
> > kernel.org stable trees with zero testing. Even minimal testing
> > would have shown that it breaks text mode VGA-console scrolling.
> > 
> > Greg, Sasha, Linus,
> > Please consider reverting that buggy patch from all affected trees.
> 
> Please work to fix it in Linus's tree first and then we will be glad to
> backport the needed fix.

FWIW, and maybe just an interesting side node: if it ever get
considered to revert the commit, this will re-introduce/re-open
CVE-2025-38213.

Cf. https://lore.kernel.org/linux-cve-announce/2025070422-CVE-2025-38213-c3e3@gregkh/T/#u

Regards,
Salvatore