The former respects the `--atexit=no` from Kamailio command line.
See note on `atexit` in TLS module "Overview".
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#### Description
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I'm using `tls` module along with some other modules. On Kamailio
termination there are a lot of "freeing already freed pointer"
messages from `qm_free()`. Also there may be a corrupted memory report
(followed by `abort()`) from `qm_debug_check_frag()`.
I'm aware of `--atexit=no` required for `tls`, and Kamailio is indeed
started as `kamailio --atexit=no -m 16 -n 1 -w . -f some.cfg`.
The `tls` module is loaded and configured something like this:
```
disable_core_dump=no
debug=2
memdbg=2
# mem_safety=0
enable_tls=yes
listen=tls:127.0.0.1:5060
mpath="lib64/kamailio/modules"
loadmodule "tls.so"
modparam("tls", "init_mode", 1)
modparam("tls", "config", "tls.cfg");
loadmodule "snmpstats.so"
modparam("snmpstats", "sipEntityType",
"proxyServer")
modparam("snmpstats", "snmpgetPath", "/usr/bin/")
modparam("snmpstats", "snmpCommunity",
"MySNMPComunity")
modparam("snmpstats", "snmpVersion", "2c")
loadmodule "xlog.so"
route {
xlog("L_NOTICE", "Hello\n");
}
```
Running Kamailio and then stopping it with `SIGTERM` yields the following.
Some blocks of shared memory are allocated by the main process (PID 62575).
E.g., one of the blocks:
```
0(62575) INFO: <core> [core/mem/q_malloc.c:429]: qm_malloc():
qm_malloc(0x7facc5dc0000, 8) returns address 0x7facc5e55810 frag.
0x7facc5e557d8 (size=8) on 1 -th hit
```
On termination, this address is freed by another process (PID 62583). Somewhere
after "sig_usr(): signal 15 received" message there's the
following entry in the log:
```
5(62583) INFO: <core> [core/mem/q_malloc.c:495]: qm_free():
qm_free(0x7facc5dc0000, 0x7facc5e55810), called from tls: tls_init.c:
ser_free(400)
```
Then later the same address is freed again, by the main process (PID 62575).
That's due to explicit call to `OPENSSL_cleanup()` from
`tls_h_mod_destroy_f()` in `tls` module:
```
0(62575) INFO: tls [tls_init.c:1063]: tls_h_mod_destroy_f(): executing openssl
v1.1+ cleanup
0(62575) INFO: <core> [core/mem/q_malloc.c:495]: qm_free():
qm_free(0x7facc5dc0000, 0x7facc5e55810), called from tls: tls_init.c:
ser_free(400)
0(62575) CRITICAL: <core> [core/mem/q_malloc.c:535]: qm_free(): BUG:
freeing already freed pointer (0x7facc5e55810), called from tls: tls_init.c:
ser_free(400), first free tls: tls_init.c: ser_free(400) - ignoring
```
It depends on initial conditions (which modules are loaded, what is the
configuration, etc.), but sometimes `qm_debug_check_frag()` detects memory
corruption and calls `abort()`:
```
0(62575) CRITICAL: <core> [core/mem/q_malloc.c:126]:
qm_debug_check_frag(): BUG: qm: fragm. 0x7facc5e891e0 (address 0x7facc5e89218)
beginning overwritten (7facc5e85498)! Memory allocator was called from tls:
tls_init.c:400. Fragment marked by :140376711102467. Exec from
core/mem/q_malloc.c:526.
```
The output of `kamcmd core.ps` suggests that the offending process (PID 62583)
is related to SNMP:
```
62575
main process - attendant
…
62583
SNMP AgentX
```
The "SNMP AgentX" process in `snmpstats` overrides some signal
handlers (including the `SIGTERM` one) and calls `exit()`:
```
/*! Creates a child that will become the AgentX sub-agent. The child will
* insulate itself from the rest of Kamailio by overriding most of signal
* handlers. */
void agentx_child(int rank)
{
…
/* Setup a SIGTERM handler */
sigfillset(&new_sigterm_handler.sa_mask);
new_sigterm_handler.sa_flags = 0;
new_sigterm_handler.sa_handler = sigterm_handler;
sigaction(SIGTERM, &new_sigterm_handler, NULL);
…
}
```
```
static void sigterm_handler(int signal)
{
/* Just exit. The master agent will clean everything up for us */
exit(0);
}
```
Looks like this `exit()` triggers an extra call to `OPENSSL_cleanup`,
implicitly armed by OpenSSL itself on startup. So, the OpenSSL cleanup gets
called twice.
As for now I've fixed the issue by replacing this `exit(0)` with
`ksr_exit(0)` which respects the `--atexit=no` command line option. But I
wonder is it a right way to do it.
As far as I can see, code in `src/modules/` ignores `ksr_exit()` and uses plain
`exit()`. Is it for a reason? Shouldn't modules also exit with `ksr_exit`?
You can view, comment on, or merge this pull request online at:
https://github.com/kamailio/kamailio/pull/3993
-- Commit Summary --
* modules/snmpstats: exit with ksr_exit() instead of standard exit()
-- File Changes --
M src/modules/snmpstats/snmpstats.c (5)
M src/modules/snmpstats/sub_agent.c (5)
-- Patch Links --
https://github.com/kamailio/kamailio/pull/3993.patch
https://github.com/kamailio/kamailio/pull/3993.diff
--
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