Re: [SR-Users] Kamailio crashing and infinite-looping when trying to free memory

Hi guys, recently we had some issues with kamailio in production, a proxy at the edge of the infrastructure was crashing seemingly randomly, it happened a couple of times in a timespan of 4-5 days until a point where we found it in an endless loop, unable to process SIP packets anymore and printing in loop messages like these: 50(60) CRITICAL: <core> [core/mem/q_malloc.c:512]: qm_free(): BUG: freeing already freed pointer (0x7ff40a359450), called from core: core/usr_avp.c: destroy_avp_list_unsafe(626), first free core: core/usr_avp.c: destroy_avp_list_unsafe(626) - ignoring 50(60) CRITICAL: <core> [core/mem/q_malloc.c:512]: qm_free(): BUG: freeing already freed pointer (0x7ff409c4fa58), called from core: core/usr_avp.c: destroy_avp_list_unsafe(626), first free core: core/usr_avp.c: destroy_avp_list_unsafe(626) - ignoring We managed to replicate the crash and the loop in a dev environment with a lot of difficulties. It seems not related to the peak load, but to the growing number of processed calls The kamailio version is: version: kamailio 5.2.2 (x86_64/linux)  flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144 MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown  compiled with gcc 5.3.1 Every time this happened it was the timer pid that was crashing or looping, we managed to get 2 core dumps of the crash and 1 of the loop (got it after killing the timer with SIGQUIT). The timer process crashes after attempting to free memory that it's not correctly managed. In particular we saw that it happens inside destroy_avp_list_unsafe() called by the tm timer, when uri_avps_from points to an invalid memory address. We don't use dialog, uac, http_async_client, but we do use topos. In the crash dumps it seems that there's something wrong inside free_cell_helper(), when trying to clean the dead_cell something goes wrong while freeing uri_avps_from, here's the crash log: 61(76) CRITICAL: <core> [core/pass_fd.c:277]: receive_fd(): EOF on 66  0(15) ALERT: <core> [main.c:740]: handle_sigs(): child process 65 exited by a signal 11  0(15) ALERT: <core> [main.c:743]: handle_sigs(): core was generated  0(15) INFO: <core> [main.c:766]: handle_sigs(): terminating due to SIGCHLD <childs getting the SIGTERM signal>  0(15) CRITICAL: <core> [core/mem/q_malloc.c:512]: qm_free(): BUG: freeing already freed pointer (0x7f4d60a2e168), called from htable: ht_api.c: ht_cell_free(217), first free core: core/usr_avp.c: destroy_avp_list_unsafe(626) - ignoring  0(15) INFO: <core> [core/sctp_core.c:53]: sctp_core_destroy(): SCTP API not initialized Before the crash we have no warnings on errors about shared memory allocation backtrace: (gdb) bt full #0  0x00000000006371d7 in destroy_avp_list_unsafe (list=0x7f34f7a411b0) at core/usr_avp.c:625         avp = 0x2         foo = 0x2         __func__ = "destroy_avp_list_unsafe" #1  0x00007f351c6909ab in free_cell_helper (dead_cell=0x7f34f7a41018, silent=0, fname=0x7f351c796a02 "timer.c", fline=689) at h_table.c:260         b = 0x0         i = 1         rpl = 0x0         tt = 0x0         foo = 0x11c68daf2         cbs = 0x0         cbs_tmp = 0x7f34f80c3790         __func__ = "free_cell_helper" #2  0x00007f351c7291e6 in wait_handler (ti=1984410416, wait_tl=0x7f34f7a410a0, data=0x7f34f7a41018) at timer.c:689         p_cell = 0x7f34f7a41018         ret = 1         unlinked = 0         rcount = 1         __func__ = "wait_handler" #3  0x00000000004d0f56 in timer_list_expire (t=1984410416, h=0x7f34f6be7850, slow_l=0x7f34f6bea368, slow_mark=2702) at core/timer.c:874         tl = 0x7f34f7a410a0         ret = 0 #4  0x00000000004d13bd in timer_handler () at core/timer.c:939         saved_ticks = 1984410416         run_slow_timer = 0         i = 654         __func__ = "timer_handler" #5  0x00000000004d1845 in timer_main () at core/timer.c:978 No locals. #6  0x0000000000425cc8 in main_loop () at main.c:1727         i = 8         pid = 0         si = 0x0         si_desc = "udp receiver child=7 sock=127.0.0.1:5060 <http://127.0.0.1:5060>\000\000\000\000q\000\000\000@6y\000\000\000\000\000\000\b\206|\210X\322:\032\301\255\000\000\000\000\000\000\000\000 \000\000\000\000\000\000\000\002\000\000\000\000\063\275{\000\000\000\000\000>", '\000' <repeats 15 times>, "\320\220\377\226\374\177\000\000\351\022a\000\000\000\000"         nrprocs = 8         woneinit = 1         __func__ = "main_loop" #7  0x000000000042ca76 in main (argc=10, argv=0x7ffc96ff9398) at main.c:2696         cfg_stream = 0x25ca010         c = -1         r = 0         tmp = 0x7ffc96ffa4c9 ""         tmp_len = -1761635728         port = 32764         proto = -1761635632         options = 0x76c598 ":f:cm:M:dVIhEeb:l:L:n:vKrRDTN:W:w:t:u:g:P:G:SQ:O:a:A:x:X:Y:"         ret = -1         seed = 1492539644         rfd = 4         debug_save = 0         debug_flag = 0         dont_fork_cnt = 2         n_lst = 0x7f351f6f6718         p = 0xffffffff <error: Cannot access memory at address 0xffffffff>         st = {st_dev = 2049, st_ino = 1282695, st_nlink = 2, st_mode = 16895, st_uid = 0, st_gid = 0, __pad0 = 0, st_rdev = 0, st_size = 4096, st_blksize = 4096, st_blocks = 8, st_atim = {tv_sec = 1552931478, tv_nsec = 972761643},            st_mtim = {tv_sec = 1552931478, tv_nsec = 972761643}, st_ctim = {tv_sec = 1552931478, tv_nsec = 972761643}, __glibc_reserved = {0, 0, 0}}         __func__ = "main" In the loop dump we have a different situation, there's a loop in the uri_avps_from structure as you can see from the next pointers: (gdb) p *dead_cell->uri_avps_from $3 = {id = 66, flags = 275, next = 0x7ff40a359450, d = {p = 0x7ff40a9ad540, l = 140686126667072, data = "@\325\232\n\364\177\000"}} (gdb) p *dead_cell->uri_avps_from.next $4 = {id = 66, flags = 275, next = 0x7ff409c4fa58, d = {p = 0x7ff40a359480, l = 140686120031360, data = "\200\224\065\n\364\177\000"}} (gdb) p *dead_cell->uri_avps_from.next.next $5 = {id = 66, flags = 275, next = 0x7ff40a359450, d = {p = 0x7ff409c4fa88, l = 140686112651912, data = "\210\372\304\t\364\177\000"}} backtrace: (gdb) bt full #0  0x00007ff43152e67e in _IO_default_xsputn () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #1  0x00007ff43150150b in vfprintf () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #2  0x00007ff431502ef1 in ?? () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #3  0x00007ff43150032d in vfprintf () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #4  0x00007ff4315087f7 in fprintf () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #5  0x0000000000686e43 in qm_free (qmp=0x7ff409336000, p=0x7ff409c4fa58, file=0x7e0a75 "core: core/usr_avp.c", func=0x7e2d70 <__func__.8439> "destroy_avp_list_unsafe", line=626, mname=0x7e0a70 "core") at core/mem/q_malloc.c:512         __llevel = -3         qm = 0x7ff409336000         f = 0x7ff409c4fa20         size = 72         next = 0x0         prev = 0x0         __func__ = "qm_free" #6  0x0000000000637209 in destroy_avp_list_unsafe (list=0x7ff409e1b6c8) at core/usr_avp.c:626         avp = 0x7ff40a359450         foo = 0x7ff409c4fa58         __func__ = "destroy_avp_list_unsafe" #7  0x00007ff42ee5d9ab in free_cell_helper (dead_cell=0x7ff409e1b530, silent=0, fname=0x7ff42ef63a02 "timer.c", fline=689) at h_table.c:260         b = 0x0         i = 1         rpl = 0x0         tt = 0x0         foo = 0x12ee5aaf2         cbs = 0x0         cbs_tmp = 0x7ff409c5d420         __func__ = "free_cell_helper" #8  0x00007ff42eef61e6 in wait_handler (ti=89094309, wait_tl=0x7ff409e1b5b8, data=0x7ff409e1b530) at timer.c:689         p_cell = 0x7ff409e1b530         ret = 1         unlinked = 0         rcount = 1         __func__ = "wait_handler" #9  0x00000000004d0f56 in timer_list_expire (t=89094309, h=0x7ff4093b4850, slow_l=0x7ff4093b8058, slow_mark=5981) at core/timer.c:874         tl = 0x7ff409e1b5b8         ret = 0 #10 0x00000000004d13bd in timer_handler () at core/timer.c:939         saved_ticks = 89094309         run_slow_timer = 0         i = 861         __func__ = "timer_handler" #11 0x00000000004d1845 in timer_main () at core/timer.c:978 No locals. #12 0x0000000000425cc8 in main_loop () at main.c:1727         i = 8         pid = 0         si = 0x0         si_desc = "udp receiver child=7 sock=127.0.0.1:5060 <http://127.0.0.1:5060>\000\000\000\000q\000\000\000@6y\000\000\000\000\000\000\032 t\220\260\242\024\032\301\255\000\000\000\000\000\000\000\000 \000\000\000\000\000\000\000\002\000\000\000\000\063\275{\000\000\000\000\000>", '\000' <repeats 15 times>, "\220\306\336\071\377\177\000\000\351\022a\000\000\000\000"         nrprocs = 8         woneinit = 1         __func__ = "main_loop" #13 0x000000000042ca76 in main (argc=10, argv=0x7fff39dec958) at main.c:2696         cfg_stream = 0x2292010         c = -1         r = 0         tmp = 0x7fff39dee4c9 ""         tmp_len = 970901552         port = 32767         proto = 970901648         options = 0x76c598 ":f:cm:M:dVIhEeb:l:L:n:vKrRDTN:W:w:t:u:g:P:G:SQ:O:a:A:x:X:Y:"         ret = -1         seed = 2710999419         rfd = 4         debug_save = 0         debug_flag = 0         dont_fork_cnt = 2         n_lst = 0x7ff431ec3718         p = 0xffffffff <error: Cannot access memory at address 0xffffffff>         st = {st_dev = 2049, st_ino = 1282695, st_nlink = 2, st_mode = 16895, st_uid = 0, st_gid = 0, __pad0 = 0, st_rdev = 0, st_size = 4096, st_blksize = 4096, st_blocks = 8, st_atim = {tv_sec = 1552931523, tv_nsec = 918435869},            st_mtim = {tv_sec = 1552994274, tv_nsec = 814438687}, st_ctim = {tv_sec = 1552994274, tv_nsec = 814438687}, __glibc_reserved = {0, 0, 0}}         __func__ = "main" We are not sure on how to keep debugging this issue which is causing some serious troubles in our environment, any help is appreciated Here you can find the dumps (beware, 12M download but 1.5G once uncompressed): https://drive.google.com/file/d/1U0LZedyona8jJZHq6HaoqXpfnU83p6Sp/view?usp=… Due thanks to Giacomo Vacca who helped us to dig into this issue. 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