[SR-Users] Core crash in del_lump() "offset exceeds message size" when using subst() inside tm:local-request route.
Daniel-Constantin Mierla
miconda at gmail.com
Mon Aug 7 09:14:55 CEST 2017
Hello,
can you make a pull request with the patch you did to terminate the
buffer with '\0'? It is a valid fix if there are situations when the
buffer is not zero-terminated.
To figure out when it is not zero-terminated, if you don't know already,
in order to analyze if it has impact on other part of code, few questions:
- are you using msg_apply_changes()?
- do you receive traffic over tcp/tls?
Cheers,
Daniel
On 31.07.17 19:43, Cody Herzog wrote:
>
> Hello.
>
>
>
> We are running Kamailio 4.3.5 on Ubuntu 14.04 LTS 64-bit.
>
>
>
> Sorry, I should have included that information in my first email.
>
>
>
> I have done more debugging, and I believe the problem is caused by the
> subst_run() function being used on a message buffer which is not null
> terminated at msg->len.
>
>
>
> The subst_f() and subst_body_f() functions both call subst_run(), and
> most of the time, everything seems fine. However, in our use case, the
> msg->buf does not always seem to be null terminated at msg->len.
>
>
>
> In other words: msg->buf[msg->len] != '\0'
>
>
>
> It seems there is sometimes some extra data in the buffer beyond
> msg->len, and subst_run() may abort() if it ever moves beyond msg->len.
>
>
>
> I found a few places in textops.c where a buffer is being temporarily
> null terminated in order to perform a regexec () search, then restored
> later, as in:
>
>
>
> body = hf->body;
>
> c = body.s[body.len];
>
> body.s[body.len] = '\0';
>
> ret = regexec((regex_t*) re, body.s, 1, &pmatch, 0);
>
> body.s[body.len] = c;
>
>
>
> I've tried making the same type of change to subst_f() and
> subst_body_f(), and now I am not seeing the crash.
>
>
>
> If I guarantee that msg->buf[msg->len] == '\0' when subst_run() is
> called, then everything seems to be OK.
>
>
>
> What do you think? Is that a valid change to make?
>
>
>
> Let me know if you'd like me to make a pull request on the main branch
> with those changes.
>
>
>
> Thanks very much.
>
> -Cody
>
>
>
>
>
>
>
>
>
>
>
>
>
> *From:*Daniel-Constantin Mierla [mailto:miconda at gmail.com]
> *Sent:* Sunday, July 30, 2017 11:12 PM
> *To:* Kamailio (SER) - Users Mailing List
> <sr-users at lists.kamailio.org>; Cody Herzog <CHerzog at IntouchHealth.com>
> *Subject:* Re: [SR-Users] Core crash in del_lump() "offset exceeds
> message size" when using subst() inside tm:local-request route.
>
>
>
> Hello,
>
> what's the version of Kamailio and the operating system you run on?
>
> Cheers,
> Daniel
>
>
>
> On 28.07.17 23:53, Cody Herzog wrote:
>
> Hello.
>
>
>
> Inside the tm:local-request route, I am trying to modify the body
> of outgoing NOTIFY messages using the subst_body() function.
>
>
>
> Things seem to work fine most of the time. The NOTIFY messages are
> correctly modified. However, I will very rarely hit a crash.
>
>
>
> I can force the crash to happen more quickly by stress testing
> with thousands of NOTIFY messages being modified.
>
>
>
> Is it safe to call subst() or subst_body() inside the
> tm:local-request route? If not, is there another way I can modify
> the outgoing NOTIFY messages safely?
>
>
>
> Note that I am also calling append_hf() inside the same
> tm:local-request route, but that has been working for a very long
> time without causing any problems. Could there be some kind of bad
> interaction between append_hf() and subst_body()?
>
>
>
> Strangely, it seems like using subst() makes the crash more likely
> to happen. For some reason, subst_body() seems to be more robust.
>
>
>
> Here are the logs I see:
>
>
>
> ---------
>
> Jul 28 10:57:40 SIPCOMM-VEGAS-TEST /usr/local/sbin/kamailio[2476]:
> CRITICAL: <core> [data_lump.c:292]: del_lump(): offset exceeds
> message size (1625 > 1194) aborting...
>
> Jul 28 10:57:43 SIPCOMM-VEGAS-TEST /usr/local/sbin/kamailio[2481]:
> CRITICAL: <core> [pass_fd.c:275]: receive_fd(): EOF on 53
>
> Jul 28 10:57:44 SIPCOMM-VEGAS-TEST /usr/local/sbin/kamailio[2367]:
> ALERT: <core> [main.c:731]: handle_sigs(): child process 2476
> exited by a signal 6
>
> Jul 28 10:57:44 SIPCOMM-VEGAS-TEST /usr/local/sbin/kamailio[2367]:
> ALERT: <core> [main.c:734]: handle_sigs(): core was generated
>
> Jul 28 10:57:44 SIPCOMM-VEGAS-TEST /usr/local/sbin/kamailio[2367]:
> INFO: <core> [main.c:756]: handle_sigs(): terminating due to SIGCHLD
>
> ---------
>
>
>
> Here is a GDB back trace from the core dump:
>
> ---------
>
> #0 0x00007fd91a567c37 in __GI_raise (sig=sig at entry=6) at
> ../nptl/sysdeps/unix/sysv/linux/raise.c:56
>
> #1 0x00007fd91a56b028 in __GI_abort () at abort.c:89
>
> #2 0x000000000044e981 in del_lump (msg=0x7fd917c5ed60 <lreq>,
> offset=1625, len=20, type=HDR_OTHER_T) at data_lump.c:293
>
> #3 0x00007fd91676297f in subst_f (msg=0x7fd917c5ed60 <lreq>,
> subst=0x7fd919e5ccc0 "\320\356\345\031\331\177", ignored=0x0) at
> textops.c:681
>
> #4 0x000000000041e1dd in do_action (h=0x7ffd364b87c0,
> a=0x7fd919e9b438, msg=0x7fd917c5ed60 <lreq>) at action.c:1059
>
> #5 0x000000000042a917 in run_actions (h=0x7ffd364b87c0,
> a=0x7fd919e9b438, msg=0x7fd917c5ed60 <lreq>) at action.c:1548
>
> #6 0x000000000042af94 in run_actions_safe (h=0x7ffd364ba5b0,
> a=0x7fd919e9b438, msg=0x7fd917c5ed60 <lreq>) at action.c:1613
>
> #7 0x0000000000549972 in rval_get_int (h=0x7ffd364ba5b0,
> msg=0x7fd917c5ed60 <lreq>, i=0x7ffd364b8b58, rv=0x7fd919e9ced8,
> cache=0x0) at rvalue.c:912
>
> #8 0x000000000054dc7c in rval_expr_eval_int (h=0x7ffd364ba5b0,
> msg=0x7fd917c5ed60 <lreq>, res=0x7ffd364b8b58, rve=0x7fd919e9ced0)
> at rvalue.c:1910
>
> #9 0x000000000041dc52 in do_action (h=0x7ffd364ba5b0,
> a=0x7fd919e9d990, msg=0x7fd917c5ed60 <lreq>) at action.c:1029
>
> #10 0x000000000042a917 in run_actions (h=0x7ffd364ba5b0,
> a=0x7fd919e9d990, msg=0x7fd917c5ed60 <lreq>) at action.c:1548
>
> #11 0x000000000041e0c4 in do_action (h=0x7ffd364ba5b0,
> a=0x7fd919e9dad8, msg=0x7fd917c5ed60 <lreq>) at action.c:1044
>
> #12 0x000000000042a917 in run_actions (h=0x7ffd364ba5b0,
> a=0x7fd919e973b8, msg=0x7fd917c5ed60 <lreq>) at action.c:1548
>
> #13 0x000000000041ab46 in do_action (h=0x7ffd364ba5b0,
> a=0x7fd919e95d70, msg=0x7fd917c5ed60 <lreq>) at action.c:677
>
> #14 0x000000000042a917 in run_actions (h=0x7ffd364ba5b0,
> a=0x7fd919e8f330, msg=0x7fd917c5ed60 <lreq>) at action.c:1548
>
> #15 0x000000000041e0c4 in do_action (h=0x7ffd364ba5b0,
> a=0x7fd919e95eb8, msg=0x7fd917c5ed60 <lreq>) at action.c:1044
>
> #16 0x000000000042a917 in run_actions (h=0x7ffd364ba5b0,
> a=0x7fd919e8c8e0, msg=0x7fd917c5ed60 <lreq>) at action.c:1548
>
> #17 0x000000000042b07d in run_top_route (a=0x7fd919e8c8e0,
> msg=0x7fd917c5ed60 <lreq>, c=0x0) at action.c:1634
>
> #18 0x00007fd917a0539a in t_uac_prepare (uac_r=0x7ffd364baf20,
> dst_req=0x7ffd364ba8f0, dst_cell=0x7ffd364ba8f8) at uac.c:391
>
> #19 0x00007fd917a07945 in t_uac_with_ids (uac_r=0x7ffd364baf20,
> ret_index=0x0, ret_label=0x0) at uac.c:599
>
> #20 0x00007fd917a07918 in t_uac (uac_r=0x7ffd364baf20) at uac.c:584
>
> #21 0x00007fd917a09b9e in req_within (uac_r=0x7ffd364baf20) at
> uac.c:802
>
> #22 0x00007fd914674052 in send_notify_request
> (subs=0x7ffd364bb200, watcher_subs=0x0, n_body=0x0,
> force_null_body=0) at notify.c:1600
>
> #23 0x00007fd9146754b3 in notify (subs=0x7ffd364bb200,
> watcher_subs=0x0, n_body=0x0, force_null_body=0) at notify.c:1690
>
> #24 0x00007fd9146cec6a in update_subscription (msg=0x7fd919efeb70,
> subs=0x7ffd364bb200, to_tag_gen=1, sent_reply=0x7ffd364bb16c) at
> subscribe.c:697
>
> #25 0x00007fd9146d45b7 in handle_subscribe (msg=0x7fd919efeb70,
> watcher_user=..., watcher_domain=...) at subscribe.c:1057
>
> #26 0x00007fd9146d08b0 in handle_subscribe0 (msg=0x7fd919efeb70)
> at subscribe.c:816
>
> #27 0x000000000041e155 in do_action (h=0x7ffd364bd680,
> a=0x7fd919e19508, msg=0x7fd919efeb70) at action.c:1053
>
> #28 0x000000000042a917 in run_actions (h=0x7ffd364bd680,
> a=0x7fd919e19508, msg=0x7fd919efeb70) at action.c:1548
>
> #29 0x000000000041e112 in do_action (h=0x7ffd364bd680,
> a=0x7fd919e19650, msg=0x7fd919efeb70) at action.c:1048
>
> #30 0x000000000042a917 in run_actions (h=0x7ffd364bd680,
> a=0x7fd919e02638, msg=0x7fd919efeb70) at action.c:1548
>
> #31 0x000000000041e0c4 in do_action (h=0x7ffd364bd680,
> a=0x7fd919e199c0, msg=0x7fd919efeb70) at action.c:1044
>
> #32 0x000000000042a917 in run_actions (h=0x7ffd364bd680,
> a=0x7fd919e199c0, msg=0x7fd919efeb70) at action.c:1548
>
> #33 0x000000000041e112 in do_action (h=0x7ffd364bd680,
> a=0x7fd919e19b08, msg=0x7fd919efeb70) at action.c:1048
>
> #34 0x000000000042a917 in run_actions (h=0x7ffd364bd680,
> a=0x7fd919df99d8, msg=0x7fd919efeb70) at action.c:1548
>
> #35 0x000000000041ab46 in do_action (h=0x7ffd364bd680,
> a=0x7fd919dbe960, msg=0x7fd919efeb70) at action.c:677
>
> #36 0x000000000042a917 in run_actions (h=0x7ffd364bd680,
> a=0x7fd919daedf8, msg=0x7fd919efeb70) at action.c:1548
>
> #37 0x000000000042b07d in run_top_route (a=0x7fd919daedf8,
> msg=0x7fd919efeb70, c=0x0) at action.c:1634
>
> #38 0x000000000050f678 in receive_msg (buf=0x7fd8f2c6ce28
> "SUBSCRIBE sip:endpoint-1720 at intouchstaging.com
> SIP/2.0\r\nRecord-Route:
> <sip:64.64.203.109:443;transport=tls;lr=on>
> <sip:64.64.203.109:443;transport=tls;lr=on>\r\nAccept:
> application/dialog-info+xml, application/pidf+xml,
> application/pidf-diff+xml,"..., len=1284, rcv_info=0x7fd8f2c6cb50)
> at receive.c:196
>
> #39 0x00000000005fb99e in receive_tcp_msg (tcpbuf=0x7fd8f2c6ce28
> "SUBSCRIBE sip:endpoint-1720 at intouchstaging.com
> SIP/2.0\r\nRecord-Route:
> <sip:64.64.203.109:443;transport=tls;lr=on>
> <sip:64.64.203.109:443;transport=tls;lr=on>\r\nAccept:
> application/dialog-info+xml, application/pidf+xml,
> application/pidf-diff+xml,"..., len=1284, rcv_info=0x7fd8f2c6cb50,
> con=0x7fd8f2c6cb38) at tcp_read.c:1207
>
> #40 0x00000000005fd48c in tcp_read_req (con=0x7fd8f2c6cb38,
> bytes_read=0x7ffd364bdb7c, read_flags=0x7ffd364bdb84) at
> tcp_read.c:1411
>
> #41 0x0000000000600aee in handle_io (fm=0x7fd919f07d80, events=1,
> idx=-1) at tcp_read.c:1643
>
> #42 0x00000000005f3ab8 in io_wait_loop_epoll (h=0xa3d3e0 <io_w>,
> t=2, repeat=0) at io_wait.h:1061
>
> #43 0x0000000000601cf7 in tcp_receive_loop (unix_sock=57) at
> tcp_read.c:1755
>
> #44 0x00000000005ea235 in tcp_init_children () at tcp_main.c:4788
>
> #45 0x00000000004ab048 in main_loop () at main.c:1675
>
> #46 0x00000000004b10c2 in main (argc=13, argv=0x7ffd364be258) at
> main.c:2566
>
> ---------
>
>
>
> Thanks very much.
>
> -Cody
>
>
>
>
> _______________________________________________
>
> Kamailio (SER) - Users Mailing List
>
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>
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>
>
>
> --
> Daniel-Constantin Mierla
> www.twitter.com/miconda <http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda <http://www.linkedin.com/in/miconda>
> Kamailio Advanced Training - www.asipto.com <http://www.asipto.com>
> Kamailio World Conference - www.kamailioworld.com <http://www.kamailioworld.com>
--
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - www.asipto.com
Kamailio World Conference - www.kamailioworld.com
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