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[Bug 1558438] Re: "Disable secure boot" workflow is broken


This bug was fixed in the package grub2 - 2.02~beta2-36ubuntu2

grub2 (2.02~beta2-36ubuntu2) xenial; urgency=medium

  * debian/postinst.in: (LP: #1558438)
    - fix quoting variables for setup_mok_validation() to account for passwords
      that might have special characters.
    - use printf rather than straight echo to pass values to mokutil.
    - ask the user to confirm password; not just write it once, this will avoid
      issues with typos in the Secure Boot keys.

 -- Mathieu Trudel-Lapierre <mathieu-tl@xxxxxxxxxx>  Fri, 18 Mar 2016
21:35:50 -0400

** Changed in: grub2 (Ubuntu Xenial)
       Status: Triaged => Fix Released

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  "Disable secure boot" workflow is broken

Status in dkms package in Ubuntu:
  Fix Released
Status in grub2 package in Ubuntu:
  Fix Released
Status in dkms source package in Xenial:
  Fix Released
Status in grub2 source package in Xenial:
  Fix Released

Bug description:
  I upgraded to grub2 2.02~beta2-36ubuntu1 and was presented with the
  new prompt to disable secure boot, since I have a dkms package
  installed.  The password I entered was 14 characters long.  On the
  terminal, I see:

  Installing for x86_64-efi platform.
  Installation finished. No error reported.
  password should be 8~16 characters
  password should be 8~16 characters
  password should be 8~16 characters

  Looking at the code:

                          db_get dkms/secureboot_key
                          length=`echo $RET | wc -c`
                          if [ $length -lt 8 ] || [ $length -gt 16 ]; then
                              db_fset dkms/text/bad_secureboot_key seen false
                              db_input critical dkms/text/bad_secureboot_key
                              STATE=$(($STATE - 2))
                          elif [ $length -ne 0 ]; then
                              echo "${RET}\n${RET}" | mokutil --disable-validation >/dev/null || true

  There are a few problems here:

   * You *must* use echo "$RET" rather than echo $RET; the password could contain metacharacters.  In general you should always surround any $-expansion in a shell script with "" unless you specifically know that you're in one of the special cases where you need to not do so.
   * This is a /bin/bash script for historical reasons.  echo "${RET}\n${RET}" is non-portable syntax and only works in shells such as dash with the other style of echo.  You should use this instead: printf '%s\n%s\n' "$RET" "$RET"
   * While you're here, it seems to me that a password confirmation page would be a good idea, given that you obviously can't see what you're typing.

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