resuming from a hibernation swap partition after the root disk was
mounted inbetween can result in file system corruption.

this doesn't happen when following the debian-installer's recommended
setup and not dual-booting, but still can happen in practical setups.


steps to reproduce
------------------

as far as i can tell, this resuming with anything happening on the disks
is not *expected* to go right, but i'll show that this can happen
inadvertedly in some setups:

* run debian 8.2 installer on a virtual machine (no gui required):
  create a /boot partition, a luks encrypted partition for swap, and a
  luks encrypted partition for / with btrfs on top.
* boot up (as expected, you're asked for the root and swap passwords)
* install pm-utils
* pm-hibernate
* (this is a good point in time to snapshot the vm)
* boot up, but mistype the swap password three times in a row.
* when systemd asks for a new swap password, wait for it to timeout.
* log in, maybe touch a new file in /, and shut down.
* boot up again, now entering the passwords correctly.
* wait for the file system corruption that has ensued to bite you, or
  provoke it like this:

(that was my reproducing setup. i've observed the same issues on my sid
production machine with kernel 4.1 as well).


other situations affected
-------------------------

apart from encrypted volumes, such a situation is assumed to occur with
other setups as well:

1) swap on external device with bad connection (eg. small fanless system
   with partitions on usb sticks or desktop with esata hard disks)

2) picking a wrong kernel on resuming that doesn't mount the swap
   partition

3) booting another os inbetween (that's an obvious then-don't-do-that for
   people who know what suspend-to-disk does,


approaches
----------

* hide bootloader after hibernating[1]. this only solves 2) and 3),
  provided that grub is the actually employed means of selecting the os.

* don't allow the prompt for a new password to expire (doesn't solve any
  of 1)/2)/3), and requires /etc/crypttab to contain the swap option,
  which might not be present on older systems)

[1] https://bugs.launchpad.net/ubuntu/+source/pm-utils/+bug/42376


how do you think such problems can be avoided? can pm-utils solve this,
or is help from the kernel / file system drivers required?


best regards
chrysn

Dear submitter,

as the package pm-utils has just been removed from the Debian archive
unstable we hereby close the associated bug reports.  We are sorry
that we couldn't deal with your issue properly.

For details on the removal, please see https://bugs.debian.org/1058701

The version of this package that was in Debian prior to this removal
can still be found using https://snapshot.debian.org/.

Please note that the changes have been done on the master archive and
will not propagate to any mirrors until the next dinstall run at the
earliest.

This message was generated automatically; if you believe that there is
a problem with it please contact the archive administrators by mailing
ftpmaster@ftp-master.debian.org.

Debian distribution maintenance software
pp.
Thorsten Alteholz (the ftpmaster behind the curtain)