Re: GNU screen "out of bounds access when setting w_xtermosc after OSC 49"

[Salvatore Bonaccorso <carnil () debian org>]

Hi

On Thu, Feb 06, 2020 at 03:04:18PM +0100, Solar Designer wrote:
> Hi,
>
> GNU screen 4.8.0 was released yesterday with a documented security fix
> in it:
>
> https://lists.gnu.org/archive/html/screen-devel/2020-02/msg00007.html
>
> ---
> From:         Amadeusz Slawinski
> Subject:      [screen-devel] GNU Screen v.4.8.0
> Date:         Wed, 5 Feb 2020 21:45:35 +0100
>
> Hello everyone,
>  
> I'm announcing availability of GNU Screen v.4.8.0
>
> Screen is a full-screen window manager that multiplexes a physical
> terminal between several processes, typically interactive shells. 
>
> This release
>   * Improves startup time by only polling for already open files to
>     close
>   * Fixes:
>        - Fix for segfault if termcap doesn't have Km entry
>        - Make screen exit code be 0 when checking --version
>        - Fix potential memory corruption when using OSC 49
>
> As last fix, fixes potential memory overwrite of quite big size (~768
> bytes), and even though I'm not sure about potential exploitability of
> that issue, I highly recommend everyone to upgrade as soon as possible.
> This issue is present at least since v.4.2.0 (haven't checked earlier).
> Thanks to pippin who brought this to my attention.

Regarding the affected versions,
https://bugzilla.redhat.com/show_bug.cgi?id=1801405#c6 points out that
the issue is caused by the upsteram commit
https://git.savannah.gnu.org/cgit/screen.git/commit/?h=screen-v4&id=c5db181b6e017cfccb8d7842ce140e59294d9f62
which would be only in v4.7.0.

Is this correct?

Regards,
Salvatore