[Dnsmasq-discuss] Floating point exception

[BENDEL, Laurent (ext.)]

Hi all,
new to dnsmasq and ipv6 so maybe I miss something. But I get a floating exception error when I launch dnsmasqd as follows :

dnsmasq -d -q -F 20:20::,20:20::FFFF:FFFF:FFFF:FFFF --enable-ra -l lease.dhcp

the exptions happens as soon as a client makes a request. Any other range I've tried is OK, just this one is problematic.

Is there anything particular with the host address FFFF:FFFF:FFFF:FFFF in ipv6 ?

I'm running openwrt on a broadcom chip.

Thanks,
Laurent

############

***@HOSTNAME:~# dnsmasq -d -q -F 20:20::,20:20::FFFF:FFFF:FFFF:FFFF --enable-ra -l lease2.dhcp
dnsmasq: started, version 2.68 cachesize 150
dnsmasq: compile time options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6 no-Lua TFTP no-conntrack ipset auth
dnsmasq-dhcp: DHCPv6, IP range 20:20:: -- 20:20::ffff:ffff:ffff:ffff, lease time 1h
dnsmasq-dhcp: router advertisement on 20:20::
dnsmasq-dhcp: IPv6 router advertisement enabled
dnsmasq: reading /etc/resolv.conf
dnsmasq: using nameserver 192.168.220.252#53
dnsmasq: using nameserver 192.168.220.252#53
dnsmasq: read /etc/hosts - 1 addresses
dnsmasq-dhcp: RTR-ADVERT(bvi1) 20:20::
dnsmasq-dhcp: RTR-ADVERT(bvi1) 20:20::
dnsmasq-dhcp: RTR-ADVERT(bvi1) 20:20::
dnsmasq-dhcp: DHCPRELEASE(bvi1) 00:03:00:06:54:ee:75:17:40:3d
dnsmasq-dhcp: DHCPSOLICIT(bvi1) 00:03:00:06:54:ee:75:17:40:3d
Floating point exception

[Simon Kelley]

The condition that causes it is having the start address all zeros and
the end address all ones. Dnsmasq calculates the size of the range, in
this case ffffffffffffff - 0 and then adds one to it, overflowing the
64-bit variable back to zero. It then divides by that zero, and falls
over in a big heap.

I've just pushed a patch to fix this. Thanks for reporting it.


Cheers.


Simon.

Hi all, new to dnsmasq and ipv6 so maybe I miss something. But I
dnsmasq -d -q -F 20:20::,20:20::FFFF:FFFF:FFFF:FFFF --enable-ra -l lease.dhcp
the exptions happens as soon as a client makes a request. Any other
range I've tried is OK, just this one is problematic.
Is there anything particular with the host address
FFFF:FFFF:FFFF:FFFF in ipv6 ?
I'm running openwrt on a broadcom chip.
Thanks, Laurent
############
20:20::,20:20::FFFF:FFFF:FFFF:FFFF --enable-ra -l lease2.dhcp
dnsmasq: started, version 2.68 cachesize 150 dnsmasq: compile time
options: IPv6 GNU-getopt no-DBus no-i18n no-IDN DHCP DHCPv6 no-Lua
-- 20:20::ffff:ffff:ffff:ffff, lease time 1h dnsmasq-dhcp: router
advertisement on 20:20:: dnsmasq-dhcp: IPv6 router advertisement
enabled dnsmasq: reading /etc/resolv.conf dnsmasq: using nameserver
192.168.220.252#53 dnsmasq: using nameserver 192.168.220.252#53
DHCPSOLICIT(bvi1) 00:03:00:06:54:ee:75:17:40:3d Floating point
exception
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