Emacs coredumps when GNUS tries to read some kinds of mails. To reproduce from 'emacs -Q', untar attached file that will create 'gnus-coredump' directory with a single mail file in it, then: $ emacs -Q M-x gnus G D ;; gnus-group-enter-directory RET GNUS then tries to open this directory as group and Emacs crashes. The backtrace and other information follows: #0 0x00007ffbe74bb5cb in raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 set = {__val = {402653184, 0 }} pid = tid = #1 0x00000000004f6f37 in terminate_due_to_signal (sig=sig@entry=6, backtrace_limit=backtrace_limit@entry=40) at ./debian/build-src/src/emacs.c:394 #2 0x0000000000511643 in emacs_abort () at ./debian/build-src/src/sysdep.c:2426 #3 0x00000000004c3f23 in x_connection_closed (dpy=dpy@entry=0x4809290, error_message=, error_message@entry=0x7ffc028a98c0 "X protocol error: BadLength (poly request too large or internal Xlib length error) on protocol request 139", ioerror=ioerror@entry=false) at ./debian/build-src/src/xterm.c:9816 dpyinfo = frame = tail = idx = #4 0x00000000004c7d49 in x_error_quitter (display=0x4809290, event=, event=) at ./debian/build-src/src/xterm.c:9904 buf = "BadLength (poly request too large or internal Xlib length error)", '\000' buf1 = "X protocol error: BadLength (poly request too large or internal Xlib length error) on protocol request 139", '\000' , "\360?", '\000' , "\360?"... #5 0x00000000004c7dcb in x_error_handler (display=0x4809290, event=0x7ffc028a9a80) at ./debian/build-src/src/xterm.c:9874 #6 0x00007ffbe94e011a in _XError () at /lib/x86_64-linux-gnu/libX11.so.6 #7 0x00007ffbe94dd077 in () at /lib/x86_64-linux-gnu/libX11.so.6 #8 0x00007ffbe94dd11d in () at /lib/x86_64-linux-gnu/libX11.so.6 #9 0x00007ffbe94dda55 in _XEventsQueued () at /lib/x86_64-linux-gnu/libX11.so.6 #10 0x00007ffbe94cf7b7 in XPending () at /lib/x86_64-linux-gnu/libX11.so.6 #11 0x00007ffbe9d7920d in () at /lib/x86_64-linux-gnu/libgdk-3.so.0 #12 0x00007ffbe9852669 in g_main_context_prepare () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #13 0x00007ffbe985306b in () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #14 0x00007ffbe9853207 in g_main_context_pending () at /lib/x86_64-linux-gnu/libglib-2.0.so.0 #15 0x00007ffbea047b9d in gtk_events_pending () at /lib/x86_64-linux-gnu/libgtk-3.so.0 #16 0x00000000004c4917 in XTread_socket (terminal=, hold_quit=0x7ffc028a9d80) at ./debian/build-src/src/xterm.c:9142 count = 0 dpyinfo = 0x48c3890 #17 0x00000000004fe1c9 in gobble_input () at ./debian/build-src/src/keyboard.c:6910 nr = hold_quit = {kind = NO_EVENT, part = scroll_bar_nowhere, code = 0, modifiers = 0, x = 0, y = 0, timestamp = 0, frame_or_window = 0, arg = 0} next = 0x0 nread = 0 err = false t = 0x114de40 #18 0x00000000004fe875 in handle_async_input () at ./debian/build-src/src/keyboard.c:7146 nread = #19 0x00000000004fe875 in process_pending_signals () at ./debian/build-src/src/keyboard.c:7160 #20 0x000000000056f5ad in maybe_quit () at ./debian/build-src/src/eval.c:1494 #21 0x00000000005766f2 in Flength (sequence=0, sequence@entry=20216131) at ./debian/build-src/src/lisp.h:1221 li = {tortoise = 20216131, max = 2, n = 0, q = 0} i = 2 val = #22 0x0000000000577739 in concat (nargs=nargs@entry=1, args=args@entry=0x7ffc028a9f38, target_type=Lisp_Cons, last_special=last_special@entry=false) at ./debian/build-src/src/fns.c:582 len = val = tail = 0 this = 20216131 toindex = toindex_byte = 0 result_len = 0 result_len_byte = 0 argnum = 0 last_tail = 0 prev = some_multibyte = false textprops = 0x0 num_textprops = 0 sa_avail = 16384 sa_count = 4 sa_must_free = false #23 0x0000000000578356 in Fcopy_sequence (arg=) at ./debian/build-src/src/lisp.h:615 #24 0x00000000004fd323 in timer_check () at ./debian/build-src/src/keyboard.c:4516 nexttime = timers = 90191187 idle_timers = tem = 0 #25 0x00000000004fd875 in readable_events (flags=flags@entry=1) at ./debian/build-src/src/keyboard.c:3340 #26 0x00000000004fe368 in get_input_pending (flags=flags@entry=1) at ./debian/build-src/src/keyboard.c:6827 #27 0x0000000000500bc8 in detect_input_pending_run_timers (do_display=do_display@entry=true) at ./debian/build-src/src/keyboard.c:9951 old_timers_run = #28 0x00000000005b0387 in wait_reading_process_output (time_limit=time_limit@entry=30, nsecs=nsecs@entry=0, read_kbd=read_kbd@entry=-1, do_display=do_display@entry=true, wait_for_cell=wait_for_cell@entry=0, wait_proc=wait_proc@entry=0x0, just_wait_proc=0) at ./debian/build-src/src/process.c:5514 old_timers_run = 41 old_buffer = 0x56fb080 old_window = 18897973 leave = false process_skipped = channel = nfds = 1 Available = {fds_bits = {32, 0 }} Writeok = {fds_bits = {0 }} check_write = check_delay = no_avail = false xerrno = 11 proc = timeout = {tv_sec = 0, tv_nsec = 0} end_time = {tv_sec = 1584075114, tv_nsec = 412240713} timer_delay = got_output_end_time = {tv_sec = 1584075114, tv_nsec = 412240713} wait = TIMEOUT got_some_output = -1 retry_for_async = count = 3 now = {tv_sec = 0, tv_nsec = -1} #29 0x00000000004244ba in sit_for (timeout=122, reading=reading@entry=true, display_option=display_option@entry=1) at ./debian/build-src/src/lisp.h:855 sec = 30 nsec = 0 do_display = true #30 0x000000000050323b in read_char (commandflag=commandflag@entry=1, map=map@entry=79079075, prev_event=0, used_mouse_menu=used_mouse_menu@entry=0x7ffc028aab5b, end_time=end_time@entry=0x0) at ./debian/build-src/src/lisp.h:944 tem0 = timeout = delay_level = 4 buffer_size = c = jmpcount = 3 local_getcjmp = {{__jmpbuf = {1, -1075357801172022359, 86242312, 79079075, 0, 140720351128656, 1075105577972157353, -1075358214119994455}, __mask_was_saved = 0, __saved_mask = {__val = {140720351127968, 91205765, 32400, 91205760, 5653333, 0, 4, 0, 91205760, 42, 0, 10, 140720351127584, 0, 0, 0}}}} save_jump = {{__jmpbuf = {0, 0, 0, 0, 0, 0, 0, 0}, __mask_was_saved = 0, __saved_mask = {__val = {0 }}}} tem = save = previous_echo_area_message = 0 also_record = 0 reread = false recorded = false polling_stopped_here = false orig_kboard = 0x486af30 #31 0x00000000005049a0 in read_key_sequence (keybuf=keybuf@entry=0x7ffc028aac50, prompt=prompt@entry=0, dont_downcase_last=dont_downcase_last@entry=false, can_return_switch_frame=can_return_switch_frame@entry=true, fix_current_buffer=fix_current_buffer@entry=true, prevent_redisplay=prevent_redisplay@entry=false, bufsize=30) at ./debian/build-src/src/keyboard.c:9147 interrupted_kboard = interrupted_frame = 0x1204c30 key = used_mouse_menu = false echo_local_start = 0 last_real_key_start = 0 keys_local_start = 0 new_binding = count = 3 t = 0 echo_start = 0 keys_start = 0 current_binding = 79079075 first_event = 0 first_unbound = 31 mock_input = 0 fkey = {parent = 15197123, map = 15197123, start = 0, end = 0} keytran = {parent = 11008659, map = 11008659, start = 0, end = 0} indec = {parent = 15197283, map = 15197283, start = 0, end = 0} shift_translated = false delayed_switch_frame = 0 original_uppercase = 0 original_uppercase_position = -1 dummyflag = false starting_buffer = 0x56fb080 fake_prefixed_keys = 0 #32 0x00000000005060a4 in command_loop_1 () at ./debian/build-src/src/lisp.h:855 cmd = keybuf = {286, 274, 0, 5989246615430861824, 0, 17483521, 4, 7818336, 10341984, 10507232, 140720351128928, 5700864, 271, 320, -920, 4, 223338299410, 0, 0, 472446402651, 511101108348, 5989246615430861824, 120, 140720351128880, 0, 11315811, -1, 5691065, 5, 31200} i = prev_modiff = 6 prev_buffer = 0x50cd760 #33 0x000000000056cd9e in internal_condition_case (bfun=bfun@entry=0x505e80 , handlers=handlers@entry=21072, hfun=hfun@entry=0x4fc780 ) at ./debian/build-src/src/eval.c:1332 val = c = 0x47e9980 #34 0x00000000004f7344 in command_loop_2 (ignore=ignore@entry=0) at ./debian/build-src/src/lisp.h:855 val = #35 0x000000000056cd0d in internal_catch (tag=tag@entry=50928, func=func@entry=0x4f7320 , arg=arg@entry=0) at ./debian/build-src/src/eval.c:1097 val = c = 0x47e9860 #36 0x00000000004f72db in command_loop () at ./debian/build-src/src/lisp.h:855 #37 0x00000000004fc363 in recursive_edit_1 () at ./debian/build-src/src/keyboard.c:695 count = 1 val = #38 0x00000000004fc6a8 in Frecursive_edit () at ./debian/build-src/src/keyboard.c:766 buffer = #39 0x000000000041a631 in main (argc=, argv=0x7ffc028ab008) at ./debian/build-src/src/emacs.c:1713 stack_bottom_variable = 0x7ffbe70181a2 <__libc_calloc+130> do_initial_setlocale = dumping = skip_args = 0 no_loadup = false junk = 0x0 dname_arg = 0x0 ch_to_dir = 0x0 original_pwd = disable_aslr = rlim = {rlim_cur = 10022912, rlim_max = 18446744073709551615} sockfd = -1 Undefined command: "xbacktrace". Try "help". In GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.24.5) of 2019-09-23, modified by Debian built on x86-grnet-01 Windowing system distributor 'The X.Org Foundation', version 11.0.12004000 System Description: Debian GNU/Linux 10 (buster) Recent messages: For information about GNU Emacs and the GNU system, type C-h C-a. Configured using: 'configure --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --enable-libsystemd --with-pop=yes --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/site-lisp:/usr/share/emacs/site-lisp --with-sound=alsa --without-gconf --with-mailutils --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --enable-libsystemd --with-pop=yes --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/26.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/26.1/site-lisp:/usr/share/emacs/site-lisp --with-sound=alsa --without-gconf --with-mailutils --with-x=yes --with-x-toolkit=gtk3 --with-toolkit-scroll-bars 'CFLAGS=-g -O2 -fdebug-prefix-map=/build/emacs-StqULU/emacs-26.1+1=. -fstack-protector-strong -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro' Configured features: XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 THREADS LIBSYSTEMD LCMS2 Important settings: value of $LC_MONETARY: en_US.UTF-8 value of $LC_NUMERIC: en_US.UTF-8 value of $LC_TIME: en_US.UTF-8 value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t global-eldoc-mode: t eldoc-mode: t electric-indent-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t transient-mark-mode: t Load-path shadows: None found. Features: (shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils elec-pair time-date mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese composite charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote dbusbind inotify lcms2 dynamic-setting system-font-setting font-render-setting move-toolbar gtk x-toolkit x multi-tty make-network-process emacs) Memory information: ((conses 16 95339 8813) (symbols 48 20366 1) (miscs 40 44 118) (strings 32 28351 1037) (string-bytes 1 743311) (vectors 16 14643) (vector-slots 8 496406 10266) (floats 8 49 99) (intervals 56 264 0) (buffers 992 11))