Package: udev
Version: 175-7
Severity: grave
Tags: d-i
Justification: causes non-serious data loss

Dear Maintainer,


I have experienced problems with udev's creation of links in /dev/disk/by-path
on multiple machines (real and
virtual) including missing links and incorrect links (ie, two partition-type
links having the same path up through
partition number, but pointing to different drives). This latter issue is of
grave concern, since anyone using
/dev/disk/by-path runs a chance of operating on the wrong block device (this
almost happened to me). The
gravity of this situation is increased due to at least ZoL (ZFS on Linux)
recommending that /dev/disk/by-path
naming be used for zpool creation; they're also plausibly used in /etc/fstab
etc.

I can trivially reproduce the problem by launching a KVM with three virtual
disks ala (for some disk image
passed as $1)

KVMOPTS="$KVMOPTS -drive file=$1-1 -drive file=$1-2"
kvm --hda "$1" -drive file="$2",if=none,id=b,boot=on -m $MEM -usb -device usb-
storage,drive=b $KVMOPTS

sda and sdb will have valid links in /dev/disk/by-path, while sdc will not have
a link.

a more complex example, illustrating the dangerous crosslinking, can be found
here:

https://groups.google.com/a/zfsonlinux.org/forum/?fromgroups=#!search/by-path
/zfs-devel/gQ5jzweYqYU/RMXiBM3x-8oJ

there's extensive logging and discussion in that thread.

I'm using a custom 3.5.3 kernel. I can and will try with a default Debian
kernel, but wanted to get the ball
rolling on this. Thanks!



-- System Information:
Debian Release: turing-β/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.5.3 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages udev depends on:
ii  debconf [debconf-2.0]  1.5.46
ii  libc6                  2.13-35
ii  libselinux1            2.1.9-5
ii  libudev0               175-7
ii  lsb-base               4.1+Debian7
ii  procps                 1:3.3.3-2
ii  util-linux             2.21.793-2

Versions of packages udev recommends:
ii  pciutils  1:3.1.9-5
ii  usbutils  1:005-3

udev suggests no packages.

-- debconf information:
  udev/new_kernel_needed: false
  udev/title/upgrade:
  udev/reboot_needed:
  udev/sysfs_deprecated_incompatibility:


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