Date:   Tue, 9 Jul 2019 03:11:35 +0200
From:   Stefan Lippers-Hollmann <s.l-h@....de>
To:     David Miller <davem@...emloft.net>
Cc:     maximmi@...lanox.com, jakub.kicinski@...ronome.com,
        kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, leonro@...lanox.com
Subject: Re: [PATCH net v2] Validate required parameters in
 inet6_validate_link_af

Hi

On 2019-05-22, David Miller wrote:
> From: Maxim Mikityanskiy <maximmi@...lanox.com>
> Date: Tue, 21 May 2019 06:40:04 +0000
>
> > inet6_set_link_af requires that at least one of IFLA_INET6_TOKEN or
> > IFLA_INET6_ADDR_GET_MODE is passed. If none of them is passed, it
> > returns -EINVAL, which may cause do_setlink() to fail in the middle of
> > processing other commands and give the following warning message:
> >
> >   A link change request failed with some changes committed already.
> >   Interface eth0 may have been left with an inconsistent configuration,
> >   please check.
> >
> > Check the presence of at least one of them in inet6_validate_link_af to
> > detect invalid parameters at an early stage, before do_setlink does
> > anything. Also validate the address generation mode at an early stage.
> >
> > Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
>
> Applied, thank you.

After updating from kernel 5.1.16 to 5.2, I noticed that my
systemd-networkd (241-5, Debian/unstable) managed bridges didn't
come up and needed a manual "ip link set dev br-lan up" to get
configured. Bisecting between v5.1 and v5.2 pointed to this
patch and reverting just this change from v5.2 fixes the issue
for me again.

$ git bisect start
# good: [e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd] Linux 5.1
git bisect good e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd
# bad: [46713c3d2f8da5e3d8ddd2249bcb1d9974fb5d28] Merge tag 'for-linus-20190706' of git://git.kernel.dk/linux-block
git bisect bad 46713c3d2f8da5e3d8ddd2249bcb1d9974fb5d28
# good: [a2d635decbfa9c1e4ae15cb05b68b2559f7f827c] Merge tag 'drm-next-2019-05-09' of git://anongit.freedesktop.org/drm/drm
git bisect good a2d635decbfa9c1e4ae15cb05b68b2559f7f827c
# good: [22c58fd70ca48a29505922b1563826593b08cc00] Merge tag 'armsoc-soc' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
git bisect good 22c58fd70ca48a29505922b1563826593b08cc00
# good: [61939b12dc24d0ac958020f261046c35a16e0c48] block: print offending values when cloned rq limits are exceeded
git bisect good 61939b12dc24d0ac958020f261046c35a16e0c48
# bad: [3510955b327176fd4cbab5baa75b449f077722a2] mm/list_lru.c: fix memory leak in __memcg_init_list_lru_node
git bisect bad 3510955b327176fd4cbab5baa75b449f077722a2
# bad: [30d1d92a888d03681b927c76a35181b4eed7071f] Merge tag 'nds32-for-linux-5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux
git bisect bad 30d1d92a888d03681b927c76a35181b4eed7071f
# bad: [dbde71df810c62e72e2aa6d88a0686a6092956cd] Merge tag 'tty-5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
git bisect bad dbde71df810c62e72e2aa6d88a0686a6092956cd
# bad: [100f6d8e09905c59be45b6316f8f369c0be1b2d8] net: correct zerocopy refcnt with udp MSG_MORE
git bisect bad 100f6d8e09905c59be45b6316f8f369c0be1b2d8
# bad: [4ca6dee5220fe2377bf12b354ef85978425c9ec7] dpaa2-eth: Make constant 64-bit long
git bisect bad 4ca6dee5220fe2377bf12b354ef85978425c9ec7
# bad: [b5730061d1056abf317caea823b94d6e12b5b4f6] cxgb4: offload VLAN flows regardless of VLAN ethtype
git bisect bad b5730061d1056abf317caea823b94d6e12b5b4f6
# bad: [c1e85c6ce57ef1eb73966152993a341c8123a8ea] net: macb: save/restore the remaining registers and features
git bisect bad c1e85c6ce57ef1eb73966152993a341c8123a8ea
# bad: [f42c104f2ec94a9255a835cd4cd1bd76279d4d06] Documentation: add TLS offload documentation
git bisect bad f42c104f2ec94a9255a835cd4cd1bd76279d4d06
# bad: [d008b3d2be4b00267e7af5c21269e7af4f65c6e2] mISDN: Fix indenting in dsp_cmx.c
git bisect bad d008b3d2be4b00267e7af5c21269e7af4f65c6e2
# bad: [40a1578d631a8ac1cf0ef797c435114107747859] ocelot: Dont allocate another multicast list, use __dev_mc_sync
git bisect bad 40a1578d631a8ac1cf0ef797c435114107747859
# bad: [7dc2bccab0ee37ac28096b8fcdc390a679a15841] Validate required parameters in inet6_validate_link_af
git bisect bad 7dc2bccab0ee37ac28096b8fcdc390a679a15841
# first bad commit: [7dc2bccab0ee37ac28096b8fcdc390a679a15841] Validate required parameters in inet6_validate_link_af

While I originally noticed this issue on real hardware (r8169, e1000,
e1000e, e100, alx) and multiple systems with a slightly complex bridge
setup, I can reproduce it with a very basic configuration under kvm
(upon which all the tests below are based):

$ cat /etc/systemd/network/20-wired.network
[Match]
Name=ens4

[Network]
DHCP=yes

(same results with just DHCP=ipv4)

With the above systemd-networkd configuration, the system comes up
without network access:

# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens4: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 00:16:3e:00:00:00 brd ff:ff:ff:ff:ff:ff

# networkctl | cat -
IDX LINK             TYPE               OPERATIONAL SETUP
  1 lo               loopback           carrier     unmanaged
  2 ens4             ether              off         configuring

2 links listed.

Manually enabling the interface does help:

# ip link set dev ens4 up

# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:16:3e:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 172.23.6.0/14 brd 172.23.255.255 scope global dynamic ens4
       valid_lft 43199sec preferred_lft 43199sec
    inet6 2003:xxxx:xxxx:xxxx::197/128 scope global tentative dynamic noprefixroute
       valid_lft 13809sec preferred_lft 1209sec
    inet6 fdxx:xxxx:xxxx::197/128 scope global tentative noprefixroute
       valid_lft forever preferred_lft forever
    inet6 fdxx:xxxx:xxxx:0:216:3eff:fe00:0/64 scope global tentative mngtmpaddr noprefixroute
       valid_lft forever preferred_lft forever
    inet6 2003:xxxx:xxxx:xxxx:216:3eff:fe00:0/64 scope global tentative dynamic mngtmpaddr noprefixroute
       valid_lft 13809sec preferred_lft 1209sec
    inet6 fe80::216:3eff:fe00:0/64 scope link
       valid_lft forever preferred_lft forever

# networkctl | cat -
IDX LINK             TYPE               OPERATIONAL SETUP
  1 lo               loopback           carrier     unmanaged
  2 ens4             ether              routable    configured

2 links listed.

A quick test of upgrading all systemd packages to 242-2 from
Debian/experimental shows the same issue; Debian 10/ buster (stable)
is shipping with systemd 241-5.

DHCPv4 is served by a recent OpenWrt/ master snapshot on ipq8065/ nbg6817
(ARMv7), using dnsmasq 2.80-13 and odhcpd-ipv6only 2019-05-17-41a74cba-3
covering DHCPv6 and prefix delegation.

Attached are xz compressed versions of the kernel configuration (amd64),
dmesg and journalctl output.

The Debian/unstable VM was started with qemu-kvm 1:3.1+dfsg-8 on a
Debian/unstable host running kernel 5.2 with this patch reverted:

$ QEMU_AUDIO_DRV=pa qemu-system-x86_64 \
	-machine accel=kvm:tcg \
	-monitor stdio \
	-rtc base=localtime \
	-cpu qemu64,+vmx \
	-smp 3 \
	-m 4096 \
	-device virtio-gpu-pci \
	-device virtio-net-pci,mac=00:16:3E:00:00:00,netdev=tap-br-lan0 \
		-netdev tap,ifname=tap-br-lan0,script=no,id=tap-br-lan0 \
	-device AC97 \
	-drive file=/srv/storage/vm/linux.qcow2.img,if=none,discard=unmap,index=0,media=disk,id=hd0 \
		-device virtio-scsi-pci,id=scsi -device scsi-hd,drive=hd0 \
	-usb \
		-device usb-tablet \
		-device usb-ehci,id=ehci \
		-device nec-usb-xhci,id=xhci \
	-device virtio-rng-pci \
	-boot menu=on

Regards
	Stefan Lippers-Hollmann

Download attachment "config.xz" of type "application/x-xz" (40048 bytes)

Download attachment "dmesg.xz" of type "application/x-xz" (10116 bytes)

Download attachment "journalctl.xz" of type "application/x-xz" (14536 bytes)

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