Hello, all. Just wanted to report on the status so far. The patch did not work, it printed a different weird (mess?) on the screen. It was not a recognizable character. Trying 0x20 resulted in a mostly blank screen. The first column had characters in it, sometimes. . Next test was to add a printk() to the routines in question. It was noted that the charcnt was zero in some (most) cases. To start were some characters, ch, between 0x20 and 0x79 inclusive (on my machine). Then a long list of ch == 0x20 and the charcnt == 0. Not sure if this is expected or if it indicates a bug somewhere else. . The charcnt variable was added by Junjie Cao in the patch that caused the problem. The patch looks like a good idea to avoid a buffer overrun. Maybe if charcnt is zero, the routine should just return early? . Let me know and I will test it out. . William Burrow. .
On Mon, Dec 22, 2025 at 11:09 AM Camaleón <[email protected]> wrote: > > El 2025-12-22 a las 11:59 +0100, Gianluca Renzi escribió: > > On 12/22/25 11:13, Helge Deller wrote: > > > On 12/22/25 11:09, Gianluca Renzi wrote: > > > > Wow! So you found the culprit. > > My deepest congrats (and a bunch of thanks) to William Burrow and > Gianluca Renzi for their finding, testing, reporting (finally, «time > spent») and the overall well job done! :-) > > > > Well, it seems pretty likely that you get the "copyright symbol", > > > because ch gets assigned "0". The question is: Why does this happen? > > > It shouldn't. > > > > > > Does it only happens with old kernels (5.x), or does it happen with > > > latest > > > Linux kernels (>= 6.8) too? > > > > > The issue is not present with the kernel 5.10.0-36-amd64, only in kernel > > 5.10.0-37-amd64 (5.10.247-1) > > > > I have a couple of Debian 12 machines laying around, and this bug is not > > present for sure. > > > > I do not remember which kernel they can have, but it's the stable Debian 12 > > version. > > (...) > > Well, I do confirm I CANNOT reproduce the «©©©©©©©©©©©©©©©©©©©©©©©©©©©©» > copyright issue neither on my Debian testing (kernel image > 6.17.9+deb14) nor Debian stable (kernel image 6.1.0-41). > > Cheers, > > -- > Camaleón
