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### Description

<!-- Explain what you did, what you expected to happen, and what actually happened. -->

I found a memory leak which is causing some issues for us in our production. I think I was able to reproduce it and determine that this is happening when we set up an MSRP connection, and that connection is closed due to inactivity (for example when `tcp_connection_lifetime` is triggered).

This issue is the same one than #2875 but with latest supported Kamailio version.

### Troubleshooting

#### Reproduction

<!-- If the issue can be reproduced, describe how it can be done. -->

In this environment we have a WebRTC SIP client, connected to Kamailio and a second party using SIP, both sending messages each via MSRP protocol. Web Client and SIP client establish a session normally, all fine here, they can communicate. At this point we have this status:

``` TESTER|centos8.4|tester21 [2021-10-11][12:49:24] [/home/vagrant]$ sudo netstat -natp | grep 10.22.22 tcp 0 0 10.22.22.21:5060 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10000 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:8080 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10001 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10002 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:8080 10.22.22.1:58530 ESTABLISHED 14653/kamailio tcp 0 0 10.22.22.21:10000 10.22.22.190:42530 ESTABLISHED 14714/kamailio tcp 0 0 10.22.22.21:8080 10.22.22.1:58532 ESTABLISHED 14704/kamailio TESTER|centos8.4|tester21 [2021-10-11][12:49:39] [/home/vagrant]$ kamcmd -s udp:127.0.0.1:2046 mod.stats core all | grep tcp tcpconn_new(1134): 199392 init_tcp(4962): 8192 init_tcp(4956): 32768 init_tcp(4947): 8 init_tcp(4940): 8 init_tcp(4933): 8 init_tcp(4927): 8 init_tcp(4915): 8

```

In order to trigger this failure much faster, I set `tcp_connection_lifetime=60`. Then we just wait 60 seconds to let the TCP connections closed. Then we finish the session, and stop our WebClient registering, so all connections are cleaned up.

``` TESTER|centos8.4|tester21 [2021-10-11][12:50:33] [/home/vagrant]$ sudo netstat -natp | grep 10.22.22 tcp 0 0 10.22.22.21:5060 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10000 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:8080 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10001 0.0.0.0:* LISTEN 14714/kamailio tcp 0 0 10.22.22.21:10002 0.0.0.0:* LISTEN 14714/kamailio TESTER|centos8.4|tester21 [2021-10-11][12:51:34] [/home/vagrant]$ kamcmd -s udp:127.0.0.1:2046 mod.stats core all | grep tcp tcpconn_new(1134): 66464 init_tcp(4962): 8192 init_tcp(4956): 32768 init_tcp(4947): 8 init_tcp(4940): 8 init_tcp(4933): 8 init_tcp(4927): 8 init_tcp(4915): 8

```

As you can see there are no connections but there is memory allocated by `tcpconn_new`. I know this is related to the MSRP because we noticed our SIP Web Client is not closing the socket, so we just wait for Kamailio to close it.

#### Debugging Data

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gdb /path/to/kamailio /path/to/corefile bt full info locals list

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``` (paste your debugging data here) ```

#### Log Messages

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``` 2021-07-25T23:54:41Z ERROR ERROR: <core> [mem/f_malloc.c:415]: fm_search_defrag(): fm_search_defrag(0x7f39a284c000, 66288); Free fragment not found! 2021-07-25T23:54:41Z ERROR ERROR: <core> [mem/f_malloc.c:498]: fm_malloc(): fm_malloc(0x7f39a284c000, 66288) called from core: tcp_main.c: tcpconn_new(957), module: core; Free fragment not found! 2021-07-25T23:54:41Z ERROR ERROR: <core> [tcp_main.c:959]: tcpconn_new(): mem. allocation failure 2021-07-25T23:54:41Z ERROR ERROR: <core> [tcp_main.c:3985]: handle_new_connect(): tcpconn_new failed, closing socket ```

#### SIP Traffic

<!-- If the issue is exposed by processing specific SIP messages, grab them with ngrep or save in a pcap file, then add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->

``` (paste your sip traffic here) ```

### Possible Solutions

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### Additional Information

* **Kamailio Version** - output of `kamailio -v`

``` version: intcc 5.5.2 (x86_64/linux) 55e232 flags: , EXTRA_DEBUGUSE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, DBG_QM_MALLOC, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED 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: 55e232 compiled on 12:15:14 Oct 11 2021 with gcc 8.4.1

```

* **Operating System**:

<!-- Details about the operating system, the type: Linux (e.g.,: Debian 8.4, Ubuntu 16.04, CentOS 7.1, ...), MacOS, xBSD, Solaris, ...; Kernel details (output of `lsb_release -a` and `uname -a`) -->

``` TESTER|centos8.4|tester21 [2021-10-11][13:52:47] [/home/vagrant]$ uname -a Linux tester21 4.18.0-305.19.1.el8_4.x86_64 #1 SMP Wed Sep 15 15:39:39 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

centos 8 ```