Bug#941326: libterm-readline-gnu-perl: segfault with shadow_redisplay

[Jakub Wilk]

Package: libterm-readline-gnu-perl
Version: 1.36-2

This used to work in buster (and earlier), but now it crashes:

  $ perl test-shadow-redisplay
  Password: ******Segmentation fault

Backtrace:

#0  0xf74d2eba in _rl_update_final () at ./display.c:2972
#1  0xf74da11d in rl_newline (count=1, key=13) at ./text.c:1105
#2  0xf74bb42d in _rl_dispatch_subseq (key=13, map=0xf74f96e0 
<emacs_standard_keymap>, got_subseq=0) at ./readline.c:852
#3  0xf74bb8a7 in _rl_dispatch (key=13, map=0xf74f96e0 <emacs_standard_keymap>) 
at ./readline.c:798
#4  0xf74bb98c in readline_internal_char () at ./readline.c:632
#5  0xf74bc21d in readline_internal_charloop () at ./readline.c:659
#6  readline_internal () at ./readline.c:671
#7  readline (prompt=0x57399d80 "\001\033[4m\002Password: \001\033[24m\002") at 
./readline.c:377
#8  0xf75159ac in XS_Term__ReadLine__Gnu__XS_rl_readline (my_perl=0x57379160, 
cv=0x574a5388) at Gnu.xs:1813
#9  0x5669007c in Perl_pp_entersub (my_perl=0x57379160) at pp_hot.c:5232
#10 0x56686009 in Perl_runops_standard (my_perl=0x57379160) at run.c:42
#11 0x565fd911 in S_run_body (oldscope=<optimized out>, my_perl=<optimized 
out>) at perl.c:2694
#12 perl_run (my_perl=0x57379160) at perl.c:2617
#13 0x565d23f4 in main (argc=<optimized out>, argv=<optimized out>, env=<optimized 
out>) at perlmain.c:122


-- System Information:
Architecture: i386

Versions of packages libterm-readline-gnu-perl depends on:
ii  perl            5.28.1-6
ii  libc6           2.29-2
ii  libreadline8    8.0-3
ii  libtinfo6       6.1+20190803-1

--
Jakub Wilk

#!/usr/bin/perl
use Term::ReadLine;
my $term = Term::ReadLine->new('');
my $attr = $term->Attribs;
$attr->{redisplay_function} = $attr->{shadow_redisplay};
my $passwd = $term->readline('Password: ');