** Description changed: + [ Impact ] + + * dnsmasq enters an infinite loop when handling a second PXE boot request when + the dhcp-range option contains a set: directive. + + * This impacts users of LTSP, for example. + + * This is a regression introduced in the recent backport of 2.91 to Jammy and + Noble. + + * In special, Ubuntu Resolute (which ships dnsmasq 2.92), is affected + by another similar bug, also related to PXE. This is also fixed by this + SRU. + + [ Test Plan ] + + * Create the following files in the current working directory: + + % cat 60-eth1.yaml + network: + version: 2 + ethernets: + eth1: + dhcp4: true + + % cat dnsmasq.conf + port=0 + log-dhcp + enable-tftp + tftp-root=/srv/tftp + interface=eth1 + bind-interfaces + dhcp-range=set:proxy,10.10.10.0,proxy,255.255.255.0 + pxe-service=x86PC,"ltsp",ltsp/ltsp.ipxe + + % cat ltsp.ipxe + #!ipxe + echo BIOS boot + shell + + * Create an isolated LXD network. + + lxc network create pxe ipv4.address=10.10.10.1/24 ipv4.dhcp=true ipv6.address=none + sudo ip tuntap add dev tap-pxe mode tap + sudo ip link set tap-pxe master pxe + sudo ip link set dev tap-pxe up + + * Deploy a dnsmasq container + + lxc launch ubuntu:jammy dnsmasq-jammy + lxc network attach pxe dnsmasq-jammy eth1 + lxc file push 60-eth1.yaml dnsmasq-jammy/etc/netplan/ + lxc exec dnsmasq-jammy -- netplan apply + + * Configure dnsmasq. If testing version from -proposed, enable it here + and install dnsmasq from -proposed. + + lxc exec dnsmasq-jammy -- apt update + lxc exec dnsmasq-jammy -- apt install -y dnsmasq + lxc exec dnsmasq-jammy -- mkdir -p /srv/tftp/ltsp + lxc file push ltsp.ipxe dnsmasq-jammy/srv/tftp/ltsp/ + lxc file push dnsmasq.conf dnsmasq-jammy/etc/ + lxc exec dnsmasq-jammy -- systemctl restart dnsmasq + + * Boot a VM that connects to the dnsmasq container. + + qemu-system-x86_64 -m 512 -nographic -netdev tap,id=n1,ifname=tap- + pxe,script=no,downscript=no -device virtio-net,netdev=n1 + + * If the VM can boot twice with no errors, the bug is fixed. + + [ Where problems could occur ] + + * The patch modifies PXE packet parsing logic. If the patch is flawed, it + could break other PXE usage. + + * The patch is not yet present upstream, and was not reviewed by the upstream + maintainer. + + [ Other Info ] + + * This bug has not been fixed upstream, and is present in every release + since 2.91. + + [ Original Report ] + Hello, Security update dnsmasq 2.91-0ubuntu0.24.04.1 broke ProxyDHCP mode. LTSP (netbooted) clients can not boot anymore. Downgrading to 2.90-2ubuntu0.4 resolves the issue. This security update is now phased 40%, please stop shipping it so the rest 60% is unaffected. Thank you. @Affected users, you can restore the previous version of dnsmasq with: sudo apt install dnsmasq=2.90-2ubuntu0.4 dnsmasq-base=2.90-2ubuntu0.4 sudo apt-mark hold dnsmasq dnsmasq-base reboot
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2166430 Title: dnsmasq 2.91-0ubuntu0.24.04.1 update broke ProxyDHCP mode To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/2166430/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
