So what is going on is this: In icmp6_receive systemd passes a buffer for control messages to recvmsg that is only big enough for the messages it expects to receive. glibc now attempts to append an extra control message to the buffer (translating SO_TIMESTAMP / COMPAT_SO_TIMESTAMP_OLD to SO_TIMESTAMP_NEW) and sets MSG_CTRUNC in flags if it can't fit this in. So this is where that EXFULL comes from.
So the fix for this is simple, right? Just pass a bigger buffer to recvmsg? No, if you do this networkd segfaults. I think __convert_scm_timestamps fails to handle a subtlety of the control message buffer, which is that the control messages don't always (it seems) occupy all of the buffer up to msg_controllen (!). If you look at the definition of CMSG_NXTHDR, the test for the end of the buffer has two clauses (https://sourceware.org/git/?p=glibc.git;a=blob;f=bits/socket.h;h=05ac0249c7da7218cbd11be99a67529161cfa7f7;hb=HEAD#l265): if ((unsigned char *) (__cmsg + 1) > ((unsigned char *) __mhdr->msg_control + __mhdr->msg_controllen) || ((unsigned char *) __cmsg + CMSG_ALIGN (__cmsg->cmsg_len) > ((unsigned char *) __mhdr->msg_control + __mhdr->msg_controllen))) /* No more entries. */ return (struct cmsghdr *) 0; I think after glibc's alterations, calling this on the last message ends up with garbage in __cmsg->cmsg_len, so __cmsg+__cmsg->cmsg_len is overflowing and the program then goes off to read uninitialized memory and hilarity ensues. I'm attaching a glibc patch which *may* help (it's building in a ppa now, will test it in a bit). But it's all a bit uncertain. Haven't filed an upstream glibc bug report yet. ** Patch added: "lp1940635.patch" https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1940635/+attachment/5521376/+files/lp1940635.patch -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1940635 Title: systemd-networkd failing to acquire a DHCP6 lease from dnsmasq on armhf Status in glibc package in Ubuntu: New Status in netplan.io package in Ubuntu: New Status in systemd package in Ubuntu: New Bug description: systemd-networkd is failing to acquire a DCHP6 lease from dnsmasq on armhf since glibc 2.34-0ubuntu1, failing systemd (tests-name=networkd- test.py) and netplan.io (test-name=ethernets) tests on armhf. Reproducer: * Setup an armhf container, e.g. via: autopkgtest systemd --test-name=networkd-test.py --shell -U --apt-pocket=proposed=src:systemd,src:glibc -s -- lxd autopkgtest/ubuntu/impish/armhf * It will fail and drop you into the shell * cd test/ && apt install python3-nose * nosetests3 -v -s -m "test_.*_dhcp_ip6" networkd-test.py This is unrelated to the recent dnsmasq changes (LP: #1894619), as that would fail on all architectures, not just armhf. It still passes inside an amd64 LXD container, so it is also not related to armhf being tested inside a container. But it shows the difference between armhf vs amd64 container, that on armhf we're missing the DHCPSOLICIT (and therefore DHCPREPLY) messages, as can be seen from the dnsmasq log: dnsmasq-dhcp[]: DHCPSOLICIT(router_eth42) 00:02:00:00:ab:11:57:1e:20:2f:9e:56:5f:34 dnsmasq-dhcp[]: DHCPREPLY(router_eth42) 2600::1f 00:02:00:00:ab:11:57:1e:20:2f:9e:56:5f:34 autopkgtest-lxd-rtypaf The issue is most probably the same that causes the currently failing netplan.io/ethernets autopkgtest on armhf, if tested against glibc 2.34-0ubuntu1. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1940635/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
