[Bug 1047666] [NEW] mkswap does not wipe filesystem signatures

[a7x]

Public bug reported:

The mkswap utility does not always clean up signatures left by other
filesystems.  This results in multiple signatures reported by 'wipefs -n
/path/to/swap/device' and prevents mountall from activating the swap
device on boot (see bug #1047659).

This bug has apparently been fixed in upstream util-linux 2.21 (which I
have not tested).  From <https://www.kernel.org/pub/linux/utils/util-
linux/v2.21/v2.21-ReleaseNotes>:

    mkswap:
       - wipe all old signatures  [Karel Zak]

The following script reproduces the problem using a loopback device:

-------------
#!/bin/sh

log() { printf %s\\n "$*"; }
error() { log "ERROR: $*" >&2; }
fatal() { error "$*"; exit 1; }
try() { "$@" || fatal "'$*' failed"; }

# this script's name
myname=$(try basename "$0") || exit 1
# temporary file for storing the swap partition
FS=${myname}.tmpfs
# which loopback device to use for ${FS}
LOOP=/dev/loop0

command -v mkfs.ufs >/dev/null \
    || fatal "mkfs.ufs not found; please install the ufsutils package"

log "creating ${LOOP} using a temporary 128MiB file..."
try dd if=/dev/zero of="${FS}" bs=1M count=128 2>/dev/null
try losetup "${LOOP}" "${FS}"
log "formatting ${LOOP} as UFS2..."
try mkfs.ufs "${LOOP}" >/dev/null
log "formatting ${LOOP} as swap..."
try mkswap "${LOOP}" >/dev/null
log "running 'wipefs -n ${LOOP}'..."
try wipefs -n "${LOOP}"
log "running 'blkid -p ${LOOP}'..."
blkid -p "${LOOP}"
log "cleaning up..."
try losetup -d "${LOOP}"
try rm "${FS}"
-------------

Note how wipefs reports multiple filesystem signatures:

offset type
----------------------------------------------------------------
0x1055c ufs [filesystem]

0xff6 swap [other]
                     UUID: 5ac922dc-3bc5-463f-a2e8-a692ee5c293a

Also note how blkid does not list the UUID of the swap device. It prints
this error message instead:

    ambivalent result (probably more filesystems on the device, use
wipefs(8) to see more details)

$ lsb_release -rd
Description: Ubuntu 12.04.1 LTS
Release: 12.04
$ apt-cache policy util-linux
util-linux:
  Installed: 2.20.1-1ubuntu3
  Candidate: 2.20.1-1ubuntu3
  Version table:
 *** 2.20.1-1ubuntu3 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status
$ apt-cache policy ufsutils
ufsutils:
  Installed: 8.2-3
  Candidate: 8.2-3
  Version table:
 *** 8.2-3 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
        100 /var/lib/dpkg/status

** Affects: util-linux (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1047666

Title:
  mkswap does not wipe filesystem signatures

Status in “util-linux” package in Ubuntu:
  New

Bug description:
  The mkswap utility does not always clean up signatures left by other
  filesystems.  This results in multiple signatures reported by 'wipefs
  -n /path/to/swap/device' and prevents mountall from activating the
  swap device on boot (see bug #1047659).

  This bug has apparently been fixed in upstream util-linux 2.21 (which
  I have not tested).  From <https://www.kernel.org/pub/linux/utils
  /util-linux/v2.21/v2.21-ReleaseNotes>:

      mkswap:
         - wipe all old signatures  [Karel Zak]

  The following script reproduces the problem using a loopback device:

  -------------
  #!/bin/sh

  log() { printf %s\\n "$*"; }
  error() { log "ERROR: $*" >&2; }
  fatal() { error "$*"; exit 1; }
  try() { "$@" || fatal "'$*' failed"; }

  # this script's name
  myname=$(try basename "$0") || exit 1
  # temporary file for storing the swap partition
  FS=${myname}.tmpfs
  # which loopback device to use for ${FS}
  LOOP=/dev/loop0

  command -v mkfs.ufs >/dev/null \
      || fatal "mkfs.ufs not found; please install the ufsutils package"

  log "creating ${LOOP} using a temporary 128MiB file..."
  try dd if=/dev/zero of="${FS}" bs=1M count=128 2>/dev/null
  try losetup "${LOOP}" "${FS}"
  log "formatting ${LOOP} as UFS2..."
  try mkfs.ufs "${LOOP}" >/dev/null
  log "formatting ${LOOP} as swap..."
  try mkswap "${LOOP}" >/dev/null
  log "running 'wipefs -n ${LOOP}'..."
  try wipefs -n "${LOOP}"
  log "running 'blkid -p ${LOOP}'..."
  blkid -p "${LOOP}"
  log "cleaning up..."
  try losetup -d "${LOOP}"
  try rm "${FS}"
  -------------

  Note how wipefs reports multiple filesystem signatures:

  offset type
  ----------------------------------------------------------------
  0x1055c ufs [filesystem]

  0xff6 swap [other]
                       UUID: 5ac922dc-3bc5-463f-a2e8-a692ee5c293a

  Also note how blkid does not list the UUID of the swap device. It
  prints this error message instead:

      ambivalent result (probably more filesystems on the device, use
  wipefs(8) to see more details)

  $ lsb_release -rd
  Description: Ubuntu 12.04.1 LTS
  Release: 12.04
  $ apt-cache policy util-linux
  util-linux:
    Installed: 2.20.1-1ubuntu3
    Candidate: 2.20.1-1ubuntu3
    Version table:
   *** 2.20.1-1ubuntu3 0
          500 http://us.archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
          100 /var/lib/dpkg/status
  $ apt-cache policy ufsutils
  ufsutils:
    Installed: 8.2-3
    Candidate: 8.2-3
    Version table:
   *** 8.2-3 0
          500 http://us.archive.ubuntu.com/ubuntu/ precise/universe amd64 Packages
          100 /var/lib/dpkg/status

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