Re: script hanging with locking bug

[RVP <rvp%SDF.ORG@localhost>]

On Tue, 25 Nov 2025, Greg Troxel wrote:

> And I find after 15 minutes of hanging:
>
>      UID   PID  PPID    CPU PRI NI      VSZ    RSS WCHAN   STAT TTY         TIME COMMAND
>    12345  1803     1  28859  29  0    17652   1072 parked  I+   pts/37   0:00.00 script -qec  true /dev/null
>
> Attaching, I see:
>
>    [Switching to LWP 1803 of process 1803]
>    0x00007f7f9aa0abba in ___lwp_park60 () from /usr/libexec/ld.elf_so
>    (gdb) bt
>    #0  0x00007f7f9aa0abba in ___lwp_park60 () from /usr/libexec/ld.elf_so
>    #1  0x00007f7f9aa05d45 in _rtld_exclusive_enter () from /usr/libexec/ld.elf_so
>    #2  0x00007f7f9aa0680d in _rtld_exit () from /usr/libexec/ld.elf_so
>    #3  0x000079176e95a6c9 in __cxa_finalize () from /usr/lib/libc.so.12
>    #4  0x000079176e95a3ed in exit () from /usr/lib/libc.so.12
>    #5  0x00000001cdc0179b in done ()
>    #6  0x00000001cdc0189a in finish ()
>    #7  <signal handler called>
>    #8  0x00007f7f9aa07ff3 in _rtld_symlook_obj () from /usr/libexec/ld.elf_so
>    #9  0x00007f7f9aa083ea in _rtld_symlook_list () from /usr/libexec/ld.elf_so
>    #10 0x00007f7f9aa0889f in _rtld_symlook_default () from /usr/libexec/ld.elf_so
>    #11 0x00007f7f9aa08d4a in _rtld_find_plt_symdef () from /usr/libexec/ld.elf_so
>    #12 0x00007f7f9aa00bc0 in _rtld_bind () from /usr/libexec/ld.elf_so
>    #13 0x00007f7f9aa0082d in _rtld_bind_start () from /usr/libexec/ld.elf_so
>    #14 0x0000000000000246 in ?? ()
>    #15 0x0000000000002d4f in ?? ()
>    #16 0x000079176e913b80 in _malloc_prefork () from /usr/lib/libc.so.12
>    #17 0x00000001cdc0213b in main ()
>
> which looks like an async-signal-safe botch leading to deadlock.
>
> But, running script outside of bup works fine.  (Bup does set
> LD_LIBRARY_PATH to pick up bup-under-test libs.)
>
> Any insight?

Looks like PR# 56254 again. script(1) should really be rewritten, but, for
now can you change `exit(status)' to `_exit(status)' here:

https://github.com/NetBSD/src/blob/trunk/usr.bin/script/script.c#L361

-RVP