netdev - PROBLEM: losing addresses if reusing interface names too fast

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:	Tue, 20 Nov 2012 12:38:16 +0100
From:	Jan Dvořák <mordae@...linux.org>
To:	netdev@...r.kernel.org
Subject: PROBLEM: losing addresses if reusing interface names too fast

(re-sent with proper subject)

Summary: If I reuse interface names too fast, I end up losing newly
         configured addresses on the new interface.

Detailed Description:

I have noticed a surprising behavior when removing virtual interfaces.
For example, removing a bridge with configured IP addresses and then
quickly creating another interface with identical name will cause the
addresses to be removed from the new interface a second or so later.

How To Reproduce:

brctl addbr foobar
ip addr add 10.20.30.40/24 dev foobar
ip addr show dev foobar

# 40: foobar: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
#     link/ether 12:12:f5:1b:c6:8e brd ff:ff:ff:ff:ff:ff
#     inet 10.20.30.40/24 scope global foobar

sleep 1

ip link set down dev foobar
brctl delbr foobar
ip link add name foobar link em1 type vlan id 42
ip addr add 10.20.30.40/24 dev foobar
ip addr show dev foobar

# 41: foobar@em1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN
#     link/ether 00:21:cc:63:ec:3c brd ff:ff:ff:ff:ff:ff
#     inet 10.20.30.40/24 scope global foobar

sleep 3

ip addr show dev foobar
# 41: foobar@em1: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN
#     link/ether 00:21:cc:63:ec:3c brd ff:ff:ff:ff:ff:ff

ip link del foobar type vlan


Other Relevant Observations:

If you monitor udev during course of this script, you will get
following sequence, spaces where sleeps were:

KERNEL[457506.286789] add      /devices/virtual/net/foobar (net)

KERNEL[457507.298630] remove   /devices/virtual/net/foobar (net)
KERNEL[457507.309597] add      /devices/virtual/net/foobar (net)

KERNEL[457510.324433] remove   /devices/virtual/net/foobar (net)


This means that I can't event wait for the bridge to get completely
removed, kernel tells me it's gone as soon as I delete it.


Could you please advise a workaround or confirm this as a bug?

Best regards,
	Jan Dvorak
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html