Hi

Sometimes I see such lines in the logs

May 10 23:15:31 mail dovecot[374]: lmtp(452): Fatal: master: service(lmtp): child 452 killed with signal 11 (core not dumped - https://dovecot.org/bugreport.html#coredumps - set /proc/sys/fs/suid_dumpable to 2) May 12 18:50:19 mail dovecot[374]: lmtp(3533): Fatal: master: service(lmtp): child 3533 killed with signal 11 (core not dumped - https://dovecot.org/bugreport.html#coredumps - set /proc/sys/fs/suid_dumpable to 2) May 13 17:21:34 mail dovecot[4910]: lmtp(5672): Fatal: master: service(lmtp): child 5672 killed with signal 11 (core dumped)

and postfix logs:

postfix/lmtp[28025]: 502DA17E1BC3: to=email@domain.com, relay=1.0.1.1[1.0.1.1]:11111, delay=0.78, delays=0.69/0/0.09/0, dsn=4.4.2, status=deferred (lost connection with 1.0.1.1[1.0.1.1] while receiving the initial server greeting)

It was the spam message

This error was in some previous versions too

Information for debugging:

dovecot is working in lxc container with Centos 8 in Proxmox

5.4.101-1-pve #1 SMP PVE 5.4.101-1 (Fri, 26 Feb 2021 13:13:09 +0100) x86_64 x86_64 x86_64 GNU/Linux

# gdb /usr/libexec/dovecot/lmtp 'core-lmtp-5672-!usr!libexec!dovecot!lmtp' GNU gdb (GDB) Red Hat Enterprise Linux 8.2-12.el8 Copyright (C) 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: http://www.gnu.org/software/gdb/bugs/. Find the GDB manual and other documentation resources online at: http://www.gnu.org/software/gdb/documentation/.

For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from /usr/libexec/dovecot/lmtp...Reading symbols from /usr/lib/debug/usr/libexec/dovecot/lmtp-2.3.14-1.0.rhel8.x86_64.debug...done. done. [New LWP 5672] [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib64/libthread_db.so.1". Core was generated by `dovecot/lmtp'. Program terminated with signal SIGSEGV, Segmentation fault. #0 __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:120 120 movdqu (%rax), %xmm4 (gdb) bt #0 __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:120 #1 0x00007fbc3f65725b in p_strdup (pool=0x5620ae47d3e0, str=0x8 ) at strfuncs.c:51 #2 0x00007fbc3f5b292a in setting_copy () at settings-parser.c:1538 #3 0x00007fbc3f5b2d8a in settings_dup_full () at settings-parser.c:1600 #4 0x00007fbc3f9547ba in mail_user_alloc (parent_event=0x0, username=0x7fbc3fa0b24a "raw mail user", set_info=0x5620ae46e458, set=0x5620ae430220) at mail-user.c:113 #5 0x00007fbc3f9a1dc5 in raw_storage_create_from_set (set_info=<optimized out>, set=<optimized out>) at raw-storage.c:25 #6 0x00005620ad66769a in client_raw_user_create (client=0x5620ae4aa8b8, client=0x5620ae4aa8b8) at lmtp-client.c:105 #7 client_create (fd_in=17, fd_out=17, conn=0x7fff7071af50) at lmtp-client.c:177 #8 0x00007fbc3f5acc99 in master_service_client_connection_callback (service=0x5620ae427130, conn=0x7fff7071af50) at master-service.c:980 #9 0x00007fbc3f5ad015 in master_service_listen (l=0x5620ae427610) at master-service.c:1212 #10 0x00007fbc3f63904d in io_loop_call_io (io=0x5620ae5032b0) at ioloop.c:714 #11 0x00007fbc3f63a679 in io_loop_handler_run_internal (ioloop=ioloop@entry=0x5620ae4272d0) at ioloop-epoll.c:222 #12 0x00007fbc3f6390f0 in io_loop_handler_run (ioloop=0x5620ae4272d0) at ioloop.c:766 #13 0x00007fbc3f639268 in io_loop_run (ioloop=0x5620ae4272d0) at ioloop.c:739 #14 0x00007fbc3f5ac557 in master_service_run (service=0x5620ae427130, callback=callback@entry=0x5620ad666fa0 ) at master-service.c:853 #15 0x00005620ad666dcd in main (argc=<optimized out>, argv=<optimized out>) at main.c:168 (gdb) bt full #0 __strlen_sse2 () at ../sysdeps/x86_64/multiarch/../strlen.S:120 No locals. #1 0x00007fbc3f65725b in p_strdup (pool=0x5620ae47d3e0, str=0x8 ) at strfuncs.c:51 mem = <optimized out> len = <optimized out> #2 0x00007fbc3f5b292a in setting_copy () at settings-parser.c:1538 strlist_info = {module_name = 0x0, defines = 0x0, defaults = 0x0, type_offset = 18446744073709551615, struct_size = 0, parent_offset = 18446744073709551615, parent = 0x0, check_func = 0x0, expand_check_func = 0x0, dependencies = 0x0, dynamic_parsers = 0x0} #3 0x00007fbc3f5b2d8a in settings_dup_full () at settings-parser.c:1600 strlist_info = {module_name = 0x0, defines = 0x0, defaults = 0x0, type_offset = 18446744073709551615, struct_size = 0, parent_offset = 18446744073709551615, parent = 0x0, check_func = 0x0, expand_check_func = 0x0, dependencies = 0x0, dynamic_parsers = 0x0} #4 0x00007fbc3f9547ba in mail_user_alloc (parent_event=0x0, username=0x7fbc3fa0b24a "raw mail user", set_info=0x5620ae46e458, set=0x5620ae430220) at mail-user.c:113 pool = 0x5620ae47d3e0 #5 0x00007fbc3f9a1dc5 in raw_storage_create_from_set (set_info=<optimized out>, set=<optimized out>) at raw-storage.c:25 user = <optimized out> ns = <optimized out> ns_set = <optimized out> mail_set = <optimized out> error = 0x7fff7071af50 "\021" #6 0x00005620ad66769a in client_raw_user_create (client=0x5620ae4aa8b8, client=0x5620ae4aa8b8) at lmtp-client.c:105 sets = <optimized out> sets = <optimized out> #7 client_create (fd_in=17, fd_out=17, conn=0x7fff7071af50) at lmtp-client.c:177 rcpt_param_extensions = {0x5620ad66be6b "XRCPTFORWARD", 0x0} cap_rcpt_forward = {name = 0x5620ad66be6b "XRCPTFORWARD", params = 0x0} workarounds = <optimized out> lmtp_set = {protocol = SMTP_PROTOCOL_SMTP, capabilities = SMTP_CAPABILITY_NONE, workarounds = (unknown: 1886498356), hostname = 0x5620ae426760 "", login_greeting = 0x1 , rawlog_dir = 0x0, ssl = 0x0, max_client_idle_time_msecs = 1886498432, max_pipelined_commands = 32767, max_bad_commands = 1062726285, max_recipients = 32700, command_limits = {max_parameters_size = 94698362529624, max_auth_size = 140446494082554, max_data_size = 140735079886496}, max_message_size = 94698362822992, mail_param_extensions = 0x2ae426758, rcpt_param_extensions = 0x7fff7071ae34, xclient_extensions = 0x7071aec0, socket_send_buffer_size = 15936827190723348992, socket_recv_buffer_size = 11513522008, event_parent = 0x5620ae46e150, debug = false, auth_optional = false, tls_required = false, mail_path_allow_broken = false, rcpt_domain_optional = false} client = 0x5620ae4aa8b8 pool = <optimized out> #8 0x00007fbc3f5acc99 in master_service_client_connection_callback (service=0x5620ae427130, conn=0x7fff7071af50) at master-service.c:980 No locals. #9 0x00007fbc3f5ad015 in master_service_listen (l=0x5620ae427610) at master-service.c:1212 service = 0x5620ae427130 conn = {fd = 17, listen_fd = 10, name = 0x5620ae4276c0 "lmtp", remote_ip = {family = 2, u = {ip6 = {__in6_u = {__u6_addr8 = "\n\000\003e", '\000' , __u6_addr16 = {10, 25859, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {1694695434, 0, 0, 0}}}, ip4 = {s_addr = 1694695434}}}, local_ip = {family = 2, u = {ip6 = {__in6_u = {__u6_addr8 = "\n\000\n\a", '\000' , __u6_addr16 = {10, 1802, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {118095882, 0, 0, 0}}}, ip4 = {s_addr = 118095882}}}, remote_port = 50660, local_port = 24, real_remote_ip = {family = 2, u = { ip6 = {__in6_u = {__u6_addr8 = "\n\000\003e", '\000' , __u6_addr16 = {10, 25859, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {1694695434, 0, 0, 0}}}, ip4 = {s_addr = 1694695434}}}, real_local_ip = {family = 2, u = {ip6 = {__in6_u = {__u6_addr8 = "\n\000\n\a", '\000' , __u6_addr16 = {10, 1802, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {118095882, 0, 0, 0}}}, ip4 = { s_addr = 118095882}}}, real_remote_port = 50660, real_local_port = 24, proxy = {hostname = 0x0, cert_common_name = 0x0, alpn = 0x0, alpn_size = 0, ssl = false, ssl_client_cert = false}, proxied = false, fifo = false, ssl = false, accepted = true} #10 0x00007fbc3f63904d in io_loop_call_io (io=0x5620ae5032b0) at ioloop.c:714 ioloop = 0x5620ae4272d0 t_id = 2 __func__ = "io_loop_call_io" #11 0x00007fbc3f63a679 in io_loop_handler_run_internal (ioloop=ioloop@entry=0x5620ae4272d0) at ioloop-epoll.c:222 ctx = 0x5620ae42c5f0 events = <optimized out> event = 0x5620ae42c670 --Type <RET> for more, q to quit, c to continue without paging--c list = 0x5620ae43adc0 io = <optimized out> tv = {tv_sec = 2147483, tv_usec = 0} events_count = <optimized out> msecs = <optimized out> ret = <optimized out> i = 0 j = <optimized out> call = <optimized out> __func__ = "io_loop_handler_run_internal" #12 0x00007fbc3f6390f0 in io_loop_handler_run (ioloop=0x5620ae4272d0) at ioloop.c:766 __func__ = "io_loop_handler_run" #13 0x00007fbc3f639268 in io_loop_run (ioloop=0x5620ae4272d0) at ioloop.c:739 __func__ = "io_loop_run" #14 0x00007fbc3f5ac557 in master_service_run (service=0x5620ae427130, callback=callback@entry=0x5620ad666fa0 ) at master-service.c:853 No locals. #15 0x00005620ad666dcd in main (argc=<optimized out>, argv=<optimized out>) at main.c:168 set_roots = {0x5620ad86e640 , 0x5620ad86e580 , 0x5620ad86e2a0 , 0x0} service_flags = <optimized out> storage_service_flags = (MAIL_STORAGE_SERVICE_FLAG_USERDB_LOOKUP | MAIL_STORAGE_SERVICE_FLAG_TEMP_PRIV_DROP | MAIL_STORAGE_SERVICE_FLAG_NO_LOG_INIT | MAIL_STORAGE_SERVICE_FLAG_NO_IDLE_TIMEOUT) tmp_base_dir = 0x5620ae41e758 "" c = <optimized out> error = 0x7fff707492d8 ""