[Dnsmasq-discuss] Floating point exception

[Simon Kelley]

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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.




On 12/02/16 16:32, BENDEL, Laurent (ext.) wrote:
> 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
> 
> ############
> 
> root at 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
> 
> 
> 
> 
> _______________________________________________ Dnsmasq-discuss
> mailing list Dnsmasq-discuss at lists.thekelleys.org.uk 
> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 

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