[Bug 53789] New: charmap.exe from ReactOS leads to heap corruption under Wine

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=53789

Bug ID: 53789
           Summary: charmap.exe from ReactOS leads to heap corruption
                    under Wine
           Product: Wine
           Version: 7.18
          Hardware: x86-64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: gdi32
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Created attachment 73279
  --> https://bugs.winehq.org/attachment.cgi?id=73279
charmap file to reproduce

Just for the record.

This crash happens with certain fonts only, I used the Fixedsys font
(https://aur.archlinux.org/packages/ttf-fixedsys-excelsior-linux)

Attaching files to reproduce, from ROS commit
9cc9a26392ea4cc246284af61185db01f8212ca9.

Problem is this line:
https://gitlab.winehq.org/wine/wine/-/blob/wine-7.18/dlls/gdi32/uniscribe/sh...
where the index is < 0

Merge request (WIP): https://gitlab.winehq.org/wine/wine/-/merge_requests/1054