lib/56767: libcurses messes up screen with MALLOC_CONF=junk:true

[roland.illig%gmx.de@localhost]

>Number:         56767
>Category:       lib
>Synopsis:       libcurses messes up screen with MALLOC_CONF=junk:true
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 26 02:15:00 +0000 2022
>Originator:     Roland Illig
>Release:        9.99.95
>Organization:
>Environment:
NetBSD nb8.roland-illig.de 9.99.95 NetBSD 9.99.95 (GENERIC) #0: Thu Mar 24 02:24:25 UTC 2022  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
In my -current environment on x86_64, I have set MALLOC_CONF=junk:true, to catch memory allocation bugs while developing.

Today I noticed that cgram(6) and ncdu(1) mess up the screen contents when I run them with TERM=xterm MALLOC_CONF=junk:true.  Without MALLOC_CONF, everything is fine.

Running ncdu with libcurses.so.8 works fine but ncdu with libcurses.so.9 doesn't remove ncdu's "Scanning..." window after scanning the files has finished.

In cgram(6) with libcurses.so.9, only the first word of each line is shown.

The bug has probably been introduced after 2021-05-01 since at that time I tested cgram thoroughly.
>How-To-Repeat:

>Fix: