When trying to start a guest with a network device in a VNet in a simple zone that has DHCP enabled - but no gateway configured - a SIGSEGV is triggered in dnsmasq. This seems to be an error in the dnsmasq dbus handler that tries to allocate a lease, which fails because there is no dhcp-range configured, and then leads to a segfault.
Avoid the situation completely by always configuring a dhcp-range, even if there is no gateway configured. Skip configuring the DHCP option that returns the router instead, which is the only place in the configure_subnet function that uses the gateway. Dnsmasq is configured to listen on an interface, so any DHCP messages that are received on this interface are dropped, because dnsmasq recognizes that there is no IP configured on this interface: Nov 26 16:35:49 ipam-test dnsmasq-dhcp[140272]: DHCP packet received on vnet1 which has no address Nov 26 16:35:57 ipam-test dnsmasq-dhcp[140272]: DHCP packet received on vnet1 which has no address An initial upstream patch to fix the segfault has been submitted here [1]. [1] https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2025q4/018342.html Signed-off-by: Stefan Hanreich <[email protected]> --- src/PVE/Network/SDN/Dhcp/Dnsmasq.pm | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm b/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm index db22e12..6a1e3b0 100644 --- a/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm +++ b/src/PVE/Network/SDN/Dhcp/Dnsmasq.pm @@ -138,9 +138,6 @@ sub add_ip_mapping { sub configure_subnet { my ($class, $config, $dhcpid, $vnetid, $subnet_config) = @_; - die "No gateway defined for subnet $subnet_config->{id}" - if !$subnet_config->{gateway}; - my $tag = $subnet_config->{id}; my ($zone, $network, $mask) = split(/-/, $tag); @@ -155,7 +152,7 @@ sub configure_subnet { my $option_string; if (ip_is_ipv6($subnet_config->{network})) { $option_string = 'option6'; - } else { + } elsif ($subnet_config->{gateway}) { $option_string = 'option'; push @{$config}, "dhcp-option=tag:$tag,$option_string:router,$subnet_config->{gateway}"; } -- 2.47.3 _______________________________________________ pve-devel mailing list [email protected] https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
