toolchain/59517: gdb sometimes randomly dumps core

[Thomas Klausner <wiz%NetBSD.org@localhost>]

>Number:         59517
>Category:       toolchain
>Synopsis:       gdb sometimes randomly dumps core
>Confidential:   yes
>Severity:       serious
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 08 06:10:00 +0000 2025
>Originator:     Thomas Klausner
>Release:        NetBSD 10.99.14
>Organization:

>Environment:
	
	
Architecture: x86_64
Machine: amd64
>Description:
Yesterday, while running a single-threaded C++ program a couple times in gdb,
I saw two gdb core dumps. One in the middle of debugging (I think
while pressing ctrl-t because the program has a signal handler I wanted
to test), but once immediately after starting gdb up.
>How-To-Repeat:
Run gdb repeatedly.

I have a core dump of one of the runs, here's the backtrace:

(gdb) bt
#0  0x000074232013a4da in _lwp_kill () from /usr/lib/libc.so.12
#1  0x0000742320145914 in abort () at /usr/src/lib/libc/stdlib/abort.c:74
#2  0x0000000000b4211b in dump_core () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/utils.c:222
#3  0x0000000000b440f5 in internal_vproblem () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/utils.c:474
#4  0x0000000000b442b8 in internal_verror () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/utils.c:500
#5  0x0000000000f5dca8 in internal_error_loc () at /usr/src/external/gpl3/gdb/lib/libgdbsupport/../../dist/gdbsupport/errors.cc:57
#6  0x0000000000b72860 in set_thread_exited () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/thread.c:252
#7  0x0000000000c400e5 in operator() () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/inferior.c:267
#8  clear_and_dispose<inferior::clear_thread_list()::<lambda(thread_info*)> > () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdbsupport/intrusive_list.h:518
#9  inferior::clear_thread_list () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/inferior.c:263
#10 0x0000000000c40c90 in exit_inferior () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/inferior.c:320
#11 0x0000000000b8e294 in generic_mourn_inferior () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/target.c:3617
#12 0x0000000000dd2bc5 in inf_child_target::mourn_inferior () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/inf-child.c:191
#13 0x0000000000dd25be in inf_ptrace_target::mourn_inferior () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/inf-ptrace.c:130
#14 0x0000000000c37c94 in handle_inferior_event () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/infrun.c:6326
#15 0x0000000000c39022 in fetch_inferior_event () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/infrun.c:4697
#16 0x0000000000c81261 in check_async_event_handlers () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/async-event.c:337
#17 0x0000000000f5847f in gdb_do_one_event () at /usr/src/external/gpl3/gdb/lib/libgdbsupport/../../dist/gdbsupport/event-loop.cc:220
#18 0x0000000000c008de in start_event_loop () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/main.c:400
#19 captured_command_loop () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/main.c:464
#20 0x0000000000c03278 in captured_main () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/main.c:1337
#21 gdb_main () at /usr/src/external/gpl3/gdb/lib/libgdb/../../dist/gdb/main.c:1356
#22 0x000000000103d2d8 in main () at /usr/src/external/gpl3/gdb/bin/gdb/../../dist/gdb/gdb.c:38

>Fix:
Please.

>Unformatted: