From Wednesday I will be on Christmas holidays, so I can help if needed
Ciao e buona giornata.
"GP! In mezzo al campo stai proprio schifoso!"
Coach M.Russo
Il lun 22 dic 2025, 11:00 Helge Deller <deller@kernel.org
<mailto:deller@kernel.org>> ha scritto:
* William Burrow <wbkernel@gmail.com <mailto:wbkernel@gmail.com>>:
> Hello, Camaleón and Salvatore.
> I have a similar problem with the TTYs and am very glad to
have found
> this message. Hopefully, my reply can make it to the list.
> .
> The offending commit was fairly easy to find as will be detailed
> later. The git bisect on the linux-stable repo found the
following
> commit as the problem:
> .
> ------------ First commit to cause the problem ------------
> commit 0998a6cb232674408a03e8561dc15aa266b2f53b
> Author: Junjie Cao <junjie.cao@intel.com
<mailto:junjie.cao@intel.com>>
> Date: Mon Oct 20 21:47:01 2025 +0800
>
> fbdev: bitblit: bound-check glyph index in bit_putcs*
>
> commit 18c4ef4e765a798b47980555ed665d78b71aeadf upstream.
> ------------ First commit to cause the problem ------------
> .
> I leave it as an exercise to the reader to solve the problem
created
> by this commit. Hopefully, soon.
Can someone please try attached patch?
Alternatively (if then another char that the "copyright symbol" is
visible), we could try replacing it by:
ch = 0x20; /* use ASCII space character */
Overall, I'm still puzzled if the original patch is correct.
I always thought fonts have 256 or 512 characters, which means the
original patch isn't necessary at all.
Helge
>From 65c6bb3e7d06dba09f6b529a2478ee818c14e6ef Mon Sep 17
00:00:00 2001
From: Helge Deller <deller@gmx.de <mailto:deller@gmx.de>>
Date: Mon, 22 Dec 2025 10:19:55 +0100
Subject: [PATCH] fbdev: bitblit: fix bound-check of glyph index
in bit_putcs*
The patch 18c4ef4e765a ("fbdev: bitblit: bound-check glyph index in
bit_putcs*") seems to trigger problems on virtual consoles, which
suddently show up with lots of copyright symbols. This is e.g.
reported
here:
https://www.reddit.com/r/debian/comments/1pnrm5t/problem_with_virtual_consoles_covered_with_a/
<https://www.reddit.com/r/debian/comments/1pnrm5t/problem_with_virtual_consoles_covered_with_a/>
Try to narrow the issue down. Here we use the "last" char of a given
font (instead of char #0), if the previous char exceeds the actual
font's glyph count.
Reported-by: Gianluca Renzi <gianlucarenzi@eurek.it
<mailto:gianlucarenzi@eurek.it>>
Signed-off-by: Helge Deller <deller@gmx.de <mailto:deller@gmx.de>>
Fixes: 18c4ef4e765a ("fbdev: bitblit: bound-check glyph index in
bit_putcs*")
diff --git a/drivers/video/fbdev/core/bitblit.c
b/drivers/video/fbdev/core/bitblit.c
index 085ffb44c51a..6b2f9748cd78 100644
--- a/drivers/video/fbdev/core/bitblit.c
+++ b/drivers/video/fbdev/core/bitblit.c
@@ -87,7 +87,7 @@ static inline void bit_putcs_aligned(struct
vc_data *vc, struct fb_info *info,
u16 ch = scr_readw(s++) & charmask;
if (ch >= charcnt)
- ch = 0;
+ ch = (charcnt - 1);
src = vc->vc_font.data + (unsigned int)ch *
cellsize;
if (attr) {
@@ -126,7 +126,7 @@ static inline void bit_putcs_unaligned(struct
vc_data *vc,
u16 ch = scr_readw(s++) & charmask;
if (ch >= charcnt)
- ch = 0;
+ ch = (charcnt - 1);
src = vc->vc_font.data + (unsigned int)ch *
cellsize;
if (attr) {