Re: [Dnsmasq-discuss] Potential memory leak

Simon Kelley Fri, 23 Jan 2026 05:50:27 -0800

This behaviour is not generally seen, so there has to be something aboutOpensense installation which is unusual. That could be the FreeBSDkernel and/or libraries, or it could be something in the dnsmasqconfiguration.

I just looked through the 2.92 changelog and the only memory leak thathas been fixed since 2.91 is in the inotify code, which isn't includedon FreebSD in 2.91.

I've just spent a while staring at the dnsmasq code that's unique to*BSD, and it's pretty difficult to see a memory leak there. It mostdoesn't allocate memory and where it does the code paths for free itagain are straightforward.

As far as configuration is concerned, there are few thinks to suspecta-priori.

Does the Opensense setup prod dnsmasq to re-read it's configurationfiles regularly? That code has historically memory-leak prone.

Does the network interface change often? Creating and deletinginterfaces/addresses/routes etc. If dnsmasq is running its routines toadapt to such changes often, that might expose a memory leak. Are yourunning --bind-interfaces or --bind-dynamic?

Since I can't really reproduce this here, and you can see it at will: itwould be useful for you to get me as much information as you can. I'llcertainly need complete dnsmasq logs: set


log-queries=extra
log-dhcp
log-facility=/path/to/file

in the config

and remove the quiet-* options that are there now.

If you can, and have enough file storage, a log file which logs the RSSof the dnsmasq process every second might be a great way to correlatestuff happening in the logs with RSS expansion.



Cheers,

Simon.





On 22.01.2026 15:33, Niten Jaiswal wrote:

The configuration below has dnsmasq’s RA feature turned off. If I turnoff radvd and turn on dnsmasq’s RA feature the same behavior occurs.

*From: *Dnsmasq-discuss <dnsmasq-discuss-[email protected]> on behalf of Simon Kelley<[email protected]>

*Date: *Thursday, January 22, 2026 at 10:30 AM

*To: *[email protected] <dnsmasq-[email protected]>

*Subject: *Re: [Dnsmasq-discuss] Potential memory leak

 From the mailing list:

"Here's something interesting... it looks like there is a problem with
serving DHCPv6... so after turning on radvd memory consumption started
increasing substantially..."

How does that alter the configuration below?


Simon.

On 22.01.2026 14:05, Niten Jaiswal via Dnsmasq-discuss wrote:
 > I’m running version 2.91_1.1 on opnsense version 25.7.10.  Below is my
 > configuration:
 >
 > OPNsense:~ # cat /usr/local/etc/dnsmasq.conf
 >
 > # DO NOT EDIT THIS FILE -- OPNsense auto-generated file
 >
 > #
 >
 >
 > rebind-localhost-ok
 >
 > stop-dns-rebind
 >
 >
 > port=5353
 >
 >
 > # If you want dnsmasq to listen for DHCP and DNS requests only on
 >
 > # specified interfaces (and the loopback) give the name of the
 >
 > # interface (eg eth0) here.
 >
 > # Repeat the line for more than one interface.
 >
 > interface=ixl1
 >
 >
 >
 >
 > dhcp-fqdn
 >
 > domain=375.jaiswal.net
 >
 > # This tells dnsmasq that a domain is local and it may answer queries
 > from /etc/hosts
 >
 > # or DHCP but should never forward queries on that domain to any
 > upstream servers.
 >
 > local=/375.jaiswal.net/
 >
 >
 > dhcp-authoritative
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 >
 > log-dhcp
 >
 > quiet-dhcp
 >
 > quiet-dhcp6
 >
 > quiet-ra
 >
 > quiet-tftp
 >
 >
 >
 > # host entries flushed via dnsmasq_watcher.py [isc] and a dump of the
 > static reservations
 >
 > addn-hosts=/var/etc/dnsmasq-hosts
 >
 > addn-hosts=/var/etc/dnsmasq-leases
 >
 >
 > dns-forward-max=15000
 >
 > cache-size=10000
 >
 > local-ttl=1
 >
 >
 > conf-dir=/usr/local/etc/dnsmasq.conf.d,*.conf
 >
 >
 > dhcp-range=tag:ixl1,X.X.X.30,X.X.X.199,86400
 >
 >
 > domain=375.jaiswal.net,X.X.X.30,X.X.X.199
 >
 > dhcp-range=tag:ixl1,::1000,::2000,constructor:ixl1,64,86400
 >
 >
 > domain=X.X.X,::1000,::2000
 >
 >
 > dhcp-host=d8:0d:17:41:af:2c,X.X.X.23,TL-SG108PE
 >
 > dhcp-host=68:1d:ef:18:b2:c6,X.X.X.29,camect-home-2fefa
 >
 > dhcp-host=dc:f5:05:18:4e:fb,X.X.X.34,mwmdemo-4EFB
 >
 > dhcp-host=1c:1d:d3:d8:23:e6,X.X.X.35,Nitens-Mac-Studio
 >
 > dhcp-host=a8:51:ab:02:3f:28,X.X.X.99,Guest_Room_AppleTV
 >
 > dhcp-host=00:1a:ae:00:40:4b,X.X.X.101
 >
 > dhcp-host=00:1a:ae:02:5f:16,X.X.X.113
 >
 > dhcp-host=88:c9:e8:bc:e9:50,X.X.X.116,Sony_A95K_FM
 >
 > dhcp-host=60:81:f9:ac:66:58,X.X.X.128,Helium-Hotspot
 >
 > dhcp-host=00:0c:d0:01:23:33,X.X.X.132
 >
 > dhcp-host=b8:2c:a0:5b:5d:14,X.X.X.142,android-a3369b84877d627a
 >
 > dhcp-host=80:a5:89:aa:42:67,X.X.X.152,mwmdemo-4267
 >
 > dhcp-host=90:56:82:98:56:c2,X.X.X.201,AmanBluesound
 >
 > dhcp-host=18:bb:26:e2:2f:43,X.X.X.202,RianBluesound
 >
 > dhcp-host=90:56:82:40:91:49,X.X.X.203,MasterBedroom
 >
 > dhcp-host=64:95:6c:0a:94:76,X.X.X.204,LG_Projector_MB
 >
 > dhcp-host=38:c9:86:14:8b:ae,X.X.X.205,10ddb198e7550000
 >
 > dhcp-host=20:f8:5e:4e:b5:d6,X.X.X.206,RianBedroomFan
 >
 > dhcp-host=20:f8:5e:4e:ac:37,X.X.X.207,AmanBedroomFan
 >
 > dhcp-host=20:f8:5e:35:e4:5c,X.X.X.208,MasterBedroomFa
 >
 > dhcp-host=20:f8:5e:4e:ce:5a,X.X.X.209,FamilyRoomFan
 >
 > dhcp-host=20:f8:5e:e4:44:ce,X.X.X.210,OfficeFan
 >
 > dhcp-host=00:11:d9:56:96:45,X.X.X.211,TIVO-A9200019027F13F
 >
 > dhcp-host=20:f8:5e:4e:ad:57,X.X.X.212,PlayRoomFan
 >
 > dhcp-host=00:1b:7c:09:81:9f,X.X.X.213,sdr35-589374
 >
 > dhcp-host=00:11:d9:8f:15:09,X.X.X.214,TIVO-849601190366E67
 >
 > dhcp-host=14:91:82:d8:4b:70,X.X.X.221,Wemo_soffit
 >
 > dhcp-host=00:1b:7c:09:81:b1,X.X.X.222,sdp55-58b1f0
 >
 > dhcp-host=d4:6a:91:0e:88:d2,X.X.X.223,Wattbox
 >
 > dhcp-host=ec:a9:07:10:7a:50,X.X.X.224,AppleTVvingRoom
 >
 > dhcp-host=4c:ab:4f:90:c6:47,X.X.X.225,AppleTVmilyRoom
 >
 > dhcp-host=c8:d0:83:ca:46:cc,X.X.X.226,MasterBAppleTV3
 >
 > dhcp-host=00:11:d9:96:e8:9a,X.X.X.227,TIVO-84900119048F1A6
 >
 > dhcp-host=id:00:01:00:01:2d:af:54:ce:b8:e6:0c:13:e7:1e,
 > [::b9cc],m1_macbook_pro
 >
 > dhcp-host=id:00:04:bb:36:4d:56:f5:2c:9f:11:50:7a:32:82:60:23:dd:e1,
 > [::bbc1],pi-hole
 >
 > dhcp-host=id:00:01:00:01:29:42:4e:a4:14:98:77:7b:27:6d,[::bbc2],mac-
 > mini-server
 >

> dhcp-host=id:00:01:00:01:2e:ea:7c:b5:00:1a:1e:04:13:98,[::bbc3],aruba-master

 >
 > dhcp-host=id:00:01:00:01:2e:ea:7c:b5:00:1a:1e:04:13:98,[::bbc3],aruba-
 > conductor
 >
 >
 > dhcp-option=tag:ixl1,60,ArubaAP
 >
 > dhcp-option=tag:ixl1,43,X.X.X.2
 >
 > dhcp-option=tag:ixl1,66,X.X.X.10
 >
 > dhcp-option=tag:ixl1,150,X.X.X.10
 >
 > dhcp-option=42,X.X.X.1
 >
 > dhcp-option=tag:ixl1,6,X.X.X.4
 >
 > dhcp-option=tag:ixl1,option6:23,[::bbc1]
 >
 >
 > # default dns mapped to this server (0.0.0.0)
 >
 > dhcp-option=6,0.0.0.0
 >
 >
 >
 > no-ident
 >
 >
 >
 > *From: *Dnsmasq-discuss <dnsmasq-discuss-
 > [email protected]> on behalf of Niten Jaiswal via Dnsmasq-
 > discuss <[email protected]>
 > *Date: *Tuesday, January 20, 2026 at 9:53 PM
 > *To: *[email protected] <dnsmasq-
 > [email protected]>
 > *Subject: *[Dnsmasq-discuss] Potential memory leak
 >
 > Hi!
 > I’m a user of opnsense and have migrated to dnsmasq for DHCPv4 and v6
 > services.  However, dnsmasq randomly stops functioning and I need to
 > manually restart it to restore DHCP services to my network.  I’ve been
 > troubleshooting the issue on the opnsense form on the following thread:

> https://forum.opnsense.org/index.php?topic=49552.30 <https://forum.opnsense.org/index.php?topic=49552.30> <https://

 > forum.opnsense.org/index.php?topic=49552.30>
 >
 > My basic testing points to an issue with serving DHCPv6 addresses.  When
 > I have router advertisement set to unmanaged the memory consumption of
 > dnsmasq was fairly stable.  When router advertisement is set to managed
 > then dnsmasq begins consuming more and more memory..
 >
 > Let me know if you need additional information.  I was asked to post to
 > the email list by an opnsense forum moderator.
 >
 > TIA
 > Niten
 >
 > _______________________________________________
 > Dnsmasq-discuss mailing list
 > [email protected]

> https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss <https://lists.thekelleys.org.uk/cgi-bin/mailman/listinfo/dnsmasq-discuss>



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Re: [Dnsmasq-discuss] Potential memory leak

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