zsh 5.1 freezes with zombie child

[Vincent Lefevre <vincent@xxxxxxxxxx>]

I did with zsh 5.1:

1. Run "emacs some_file &"
2. Run "less some_other_file"
3. Quit emacs.
4. Quit less.

The result is a frozen zsh with a zombie child corresponding to less.
100% reproducible.

The backtrace:

(gdb) bt
#0  0x00007f6cd1c35446 in do_sigsuspend (set=0x7ffc2716e9e0)
    at ../sysdeps/unix/sysv/linux/sigsuspend.c:31
#1  __GI___sigsuspend (set=set@entry=0x7ffc2716e9e0)
    at ../sysdeps/unix/sysv/linux/sigsuspend.c:41
#2  0x00000000004787f6 in signal_suspend (sig=sig@entry=17, 
    wait_cmd=wait_cmd@entry=0) at ../../Src/signals.c:375
#3  0x0000000000448ca6 in zwaitjob (job=<optimized out>, wait_cmd=0)
    at ../../Src/jobs.c:1453
#4  0x0000000000449367 in waitjobs () at ../../Src/jobs.c:1505
#5  0x000000000042cb1b in execpline (state=state@entry=0x7ffc27170610, 
    slcode=<optimized out>, how=<optimized out>, how@entry=18, last1=0)
    at ../../Src/exec.c:1601
#6  0x000000000042db2d in execlist (state=state@entry=0x7ffc27170610, 
    dont_change_job=dont_change_job@entry=1, exiting=exiting@entry=0)
    at ../../Src/exec.c:1283
#7  0x000000000045139b in execif (state=0x7ffc27170610, do_exec=0)
    at ../../Src/loop.c:565
#8  0x000000000042a4c1 in execcmd (state=state@entry=0x7ffc27170610, 
    input=input@entry=0, output=output@entry=0, how=<optimized out>, 
    how@entry=18, last1=2) at ../../Src/exec.c:3472
#9  0x000000000042be7e in execpline2 (state=state@entry=0x7ffc27170610, 
    pcode=pcode@entry=579, how=how@entry=18, input=0, output=0, 
    last1=last1@entry=0) at ../../Src/exec.c:1746
#10 0x000000000042c241 in execpline (state=state@entry=0x7ffc27170610, 
    slcode=<optimized out>, how=how@entry=18, last1=0) at ../../Src/exec.c:1524
#11 0x000000000042db2d in execlist (state=state@entry=0x7ffc27170610, 
    dont_change_job=dont_change_job@entry=1, exiting=exiting@entry=0)
    at ../../Src/exec.c:1283
#12 0x000000000042df00 in execode (p=p@entry=0x13871c0, 
    dont_change_job=dont_change_job@entry=1, exiting=exiting@entry=0, 
    context=context@entry=0x495257 "shfunc") at ../../Src/exec.c:1074
#13 0x000000000042ea19 in runshfunc (prog=0x13871c0, wrap=0x0, 
    name=0x7f6cd2af8d90 "mless") at ../../Src/exec.c:5356
#14 0x000000000042f355 in doshfunc (shfunc=shfunc@entry=0x132e320, 
    doshargs=doshargs@entry=0x7f6cd2af8d28, noreturnval=noreturnval@entry=0)
    at ../../Src/exec.c:5222
#15 0x000000000042f71f in execshfunc (shf=shf@entry=0x132e320, 
    args=args@entry=0x7f6cd2af8d28) at ../../Src/exec.c:4853
#16 0x000000000042b53b in execshfunc (args=0x7f6cd2af8d28, shf=0x132e320)
    at ../../Src/exec.c:4819
#17 execcmd (state=state@entry=0x7ffc27172280, input=input@entry=0, 
    output=output@entry=0, how=<optimized out>, how@entry=18, last1=2)
    at ../../Src/exec.c:3524
#18 0x000000000042be7e in execpline2 (state=state@entry=0x7ffc27172280, 
    pcode=pcode@entry=2499, how=how@entry=18, input=0, output=0, 
    last1=last1@entry=0) at ../../Src/exec.c:1746
#19 0x000000000042c241 in execpline (state=state@entry=0x7ffc27172280, 
    slcode=<optimized out>, how=how@entry=18, last1=0) at ../../Src/exec.c:1524
#20 0x000000000042db2d in execlist (state=state@entry=0x7ffc27172280, 
    dont_change_job=dont_change_job@entry=0, exiting=exiting@entry=0)
    at ../../Src/exec.c:1283
#21 0x000000000042df00 in execode (p=p@entry=0x7f6cd2af8bb8, 
    dont_change_job=dont_change_job@entry=0, exiting=exiting@entry=0, 
    context=context@entry=0x496791 "toplevel") at ../../Src/exec.c:1074
#22 0x00000000004417c9 in loop (toplevel=toplevel@entry=1, 
    justonce=justonce@entry=0) at ../../Src/init.c:208
#23 0x0000000000444c1e in zsh_main (argc=<optimized out>, argv=<optimized out>)
    at ../../Src/init.c:1678
#24 0x00007f6cd1c21b45 in __libc_start_main (main=0x4105c0 <main>, argc=1, 
    argv=0x7ffc271725c8, init=<optimized out>, fini=<optimized out>, 
    rtld_fini=<optimized out>, stack_end=0x7ffc271725b8) at libc-start.c:287
#25 0x00000000004105ee in _start ()

-- 
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)