[Dnsmasq-discuss] dnsmasq 2.86 crash
Eloy Paris
peloy at chapus.net
Wed Oct 13 04:03:48 UTC 2021
Sorry, I forgot the backtrace; here it is:
(gdb) bt
#0 0x0000561772564d46 in lookup_domain (domain=0x561772b1d7a0 "enterprise.activity.windows.com", flags=flags at entry=128,
lowout=lowout at entry=0x7ffe8a4b63ac, highout=highout at entry=0x7ffe8a4b63b0) at domain-match.c:234
#1 0x0000561772532b1e in forward_query (udpfd=5, udpaddr=udpaddr at entry=0x7ffe8a4b6500, dst_addr=dst_addr at entry=0x7ffe8a4b64e0,
dst_iface=dst_iface at entry=13, header=header at entry=0x561772b1fae0, plen=plen at entry=49, limit=0x561772b1fce0 "", now=1634091453,
forward=0x0, ad_reqd=0, do_bit=0) at forward.c:258
#2 0x000056177253387e in receive_query (listen=listen at entry=0x561772b1f400, now=now at entry=1634091453) at forward.c:1636
#3 0x0000561772538b7c in check_dns_listeners (now=now at entry=1634091453) at dnsmasq.c:1810
#4 0x000056177251888b in main (argc=<optimized out>, argv=<optimized out>) at dnsmasq.c:1237
(gdb)
On Tue, Oct 12, 2021 at 10:55:22PM -0400, Eloy Paris wrote:
> Hello,
>
> I am experiencing crashes in dnsmasq (2.86). I am able to reproduce it
> though I am not sure about the exact sequence of events -- it happens
> when I enable/disable my Ethernet NIC and disable/enable my wireless
> NIC.
>
> In this use case, dnsmasq provides DNS and DHCP for a virtual machine
> (VM) running on KVM. Something like this:
>
> +-- (Ethernet)-+
> | |
> Internet + Hypervisor (virbr0) --- VM
> | |
> +--- (Wi-fi)---+
>
> The interfaces I am enabling and disabling are on the hypervisor
> ("Ethernet" and "Wi-fi" above; virbr0 never goes down).
>
> I guess dnsmasq does not handle gracefully receiving a DNS request from
> the VM when the external interfaces of the hypervisor (Ethernet or
> wi-fi) go down?
>
> Some details below; happy to provide more information if that's not
> enough to get to the bottom of it.
>
> Cheers,
>
> Eloy Paris.-
>
> ----------------------------------------------------------------------
>
> elparis at chapilu[0]:~$ sudo coredumpctl debug dnsmasq
> [sudo] Mot de passe de elparis :
> PID: 46002 (dnsmasq)
> UID: 65534 (nobody)
> GID: 65534 (nobody)
> Signal: 11 (SEGV)
> Timestamp: Tue 2021-10-12 22:17:33 EDT (11min ago)
> Command Line: /usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-ro --dhcp-script=/usr/lib/libvirt/libvirt_leaseshelper
> Executable: /usr/bin/dnsmasq
> Control Group: /system.slice/libvirtd.service
> Unit: libvirtd.service
> Slice: system.slice
> Boot ID: a42fe0fbd18649ad8a6951687e2855d8
> Machine ID: 3d34409507634591951da9abb51a3942
> Hostname: chapilu
> Storage: /var/lib/systemd/coredump/core.dnsmasq.65534.a42fe0fbd18649ad8a6951687e2855d8.46002.1634091453000000.zst (present)
> Disk Size: 204.6K
> Message: Process 46002 (dnsmasq) of user 65534 dumped core.
>
> Found module linux-vdso.so.1 with build-id: c6d7bcf242640b81aef03f231535fa4c2486c744
> Found module libffi.so.7 with build-id: de60e99f39569d11d09160bbdcd486cedc87d2b6
> Found module libp11-kit.so.0 with build-id: 5314ec746546ada6f442b6fdfae15eab9f6d3cdc
> Found module libcrypto.so.1.1 with build-id: 6d23f0a3f354825868d044684fad31d482cc9210
> Found module libdl.so.2 with build-id: 5abc547e7b0949f89f3c0e21ab0c8331a7440a8a
> Found module libcrypt.so.2 with build-id: 3743451bdaf36f951f926927633fd964813025d0
> Found module libnss_systemd.so.2 with build-id: 22990ff716d182c427e26b7a3cf94048b55b3e75
> Found module libnss_files.so.2 with build-id: 1a36dfc01d3a1010b2ee79766a24a8090a3266d5
> Found module libgpg-error.so.0 with build-id: ba85170c2d9343ea05eea8fa2048c212ff4ef552
> Found module libgcrypt.so.20 with build-id: db45f5d5e0f7af1e77324fea1885f974619ad268
> Found module libcap.so.2 with build-id: c1674f9082fedd415876b9f7d9712269163259b5
> Found module liblz4.so.1 with build-id: e63600ab23b2f6997f42fac2fa56e1f02ce159a1
> Found module libzstd.so.1 with build-id: 4b10444c1560ebc574af4d5f488b7408b22d450e
> Found module liblzma.so.5 with build-id: 8b615460aa230708c5183f16bede67aa0437d95e
> Found module librt.so.1 with build-id: 75484da2d6f1515189eefa076e0a40328834cd16
> Found module ld-linux-x86-64.so.2 with build-id: 040cc3dd10461562f177df39e3be2f3704258c3c
> Found module libmnl.so.0 with build-id: fdf3a318247060fa3e451d511ebaf23a7396d1dd
> Found module libnfnetlink.so.0 with build-id: 273cc877c7b2ff41e88753edda777d7f1c4017ca
> Found module libunistring.so.2 with build-id: 015ac6d6bcb60b7d8bea31a80d1941b06e8636ab
> Found module libsystemd.so.0 with build-id: f776aaa16b4e2ba7056d01d928e4b2726ffe2b8b
> Found module libpthread.so.0 with build-id: 07c8f95b4f3251d08550217ad8a1f31066229996
> Found module libc.so.6 with build-id: 4b406737057708c0e4c642345a703c47a61c73dc
> Found module libgmp.so.10 with build-id: e58d34ab389d1b649c24195c2d145e3ff2e58290
> Found module libhogweed.so.6 with build-id: 2d70cff7b1841b4d9ca4e8e7726cd4b944c07fdc
> Found module libnettle.so.8 with build-id: 9a878e513c02007598fcf1e2e286c2203f13536e
> Found module libnetfilter_conntrack.so.3 with build-id: 0ad526380b1a1986a1e471a84d88d5f2a7fedd80
> Found module libidn2.so.0 with build-id: 1ce2b50ad9f9821c2c629b521cf5a3c99593d332
> Found module libdbus-1.so.3 with build-id: 74f2ab9c60512f3a93c932c3f627564d42e0b11e
> Found module dnsmasq with build-id: 17b49d0999133997748526c51d99bf8b932fb79d
> Stack trace of thread 46002:
> #0 0x0000561772564d46 lookup_domain (dnsmasq + 0x55d46)
> #1 0x0000561772532b1e forward_query (dnsmasq + 0x23b1e)
> #2 0x000056177253387e receive_query (dnsmasq + 0x2487e)
> #3 0x0000561772538b7c check_dns_listeners (dnsmasq + 0x29b7c)
> #4 0x000056177251888b main (dnsmasq + 0x988b)
> #5 0x00007f85147e4b25 __libc_start_main (libc.so.6 + 0x27b25)
> #6 0x00005617725197ae _start (dnsmasq + 0xa7ae)
>
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> Reading symbols from /usr/bin/dnsmasq...
> [New LWP 46002]
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/usr/lib/libthread_db.so.1".
> Core was generated by `/usr/bin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf --leasefile-'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0 0x0000561772564d46 in lookup_domain (domain=0x561772b1d7a0 "enterprise.activity.windows.com", flags=flags at entry=128,
> lowout=lowout at entry=0x7ffe8a4b63ac, highout=highout at entry=0x7ffe8a4b63b0) at domain-match.c:234
> 234 domain-match.c: Aucun fichier ou dossier de ce type.
> (gdb)
>
>
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