group.of.nepali.translators team mailing list archive

[Launchpad Bug Tracker <1401532@xxxxxxxxxxxxxxxxxx>]

This bug was fixed in the package grub2 - 2.02~beta2-36ubuntu3.26

---------------
grub2 (2.02~beta2-36ubuntu3.26) xenial; urgency=medium

  [ Chris Coulson ]
  * SECURITY UPDATE: Heap buffer overflow when encountering commands that
    cannot be tokenized to less than 8192 characters.
    - 0082-yylex-Make-lexer-fatal-errors-actually-be-fatal.patch: Make
      fatal lexer errors actually be fatal
    - CVE-2020-10713
  * SECURITY UPDATE: Multiple integer overflow bugs that could result in
    heap buffer allocations that were too small and subsequent heap buffer
    overflows when handling certain filesystems, font files or PNG images.
    - 0083-safemath-Add-some-arithmetic-primitives-that-check-f.patch: Add
      arithmetic primitives that allow for overflows to be detected
    - 0084-calloc-Make-sure-we-always-have-an-overflow-checking.patch:
      Make sure that there is always an overflow checking implementation
      of calloc() available
    - 0085-calloc-Use-calloc-at-most-places.patch: Use calloc where
      appropriate
    - 0086-malloc-Use-overflow-checking-primitives-where-we-do-.patch: Use
      overflow-safe arithmetic primitives when performing allocations
      based on the results of operations that might overflow
    - 0094-hfsplus-fix-two-more-overflows.patch: Fix integer overflows in
      hfsplus
    - 0095-lvm-fix-two-more-potential-data-dependent-alloc-over.patch: Fix
      more potential integer overflows in lvm
    - CVE-2020-14308, CVE-2020-14309, CVE-2020-14310, CVE-2020-14311
  * SECURITY UPDATE: Use-after-free when executing a command that causes
    a currently executing function to be redefined.
    - 0092-script-Remove-unused-fields-from-grub_script_functio.patch:
      Remove unused fields from grub_script_function
    - 0093-script-Avoid-a-use-after-free-when-redefining-a-func.patch:
      Avoid a use-after-free when redefining a function during execution
    - CVE-2020-15706
  * SECURITY UPDATE: Integer overflows that could result in heap buffer
    allocations that were too small and subsequent heap buffer overflows
    during initrd loading.
    - 0105-linux-Fix-integer-overflows-in-initrd-size-handling.patch: Fix
      integer overflows in initrd size handling
    - 0106-efilinux-Fix-integer-overflows-in-grub_cmd_initrd.patch: Fix
      integer overflows in linuxefi grub_cmd_initrd
    - CVE-2020-15707
  * Various fixes as a result of code review and static analysis:
    - 0087-iso9660-Don-t-leak-memory-on-realloc-failures.patch: Fix a
     memory leak on realloc failures when processing symbolic links
    - 0088-font-Do-not-load-more-than-one-NAME-section.patch: Fix a
      memory leak when processing font files with more than one NAME
      section
    - 0089-gfxmenu-Fix-double-free-in-load_image.patch: Zero self->bitmap
      after it is freed in order to avoid a potential double free later on
    - 0090-lzma-Make-sure-we-don-t-dereference-past-array.patch: Fix an
      out-of-bounds read in LzmaEncode
    - 0091-tftp-Do-not-use-priority-queue.patch: Refactor tftp to not use
      priority queues and fix a double free
    - 0096-efi-fix-some-malformed-device-path-arithmetic-errors.patch: Fix
      various arithmetic errors with malformed device paths
    - 0098-Fix-a-regression-caused-by-efi-fix-some-malformed-de.patch: Fix
      a NULL deref in the chainloader command introduced by a previous
      patch
    - 0100-chainloader-Avoid-a-double-free-when-validation-fail.patch:
      Avoid a double free in the chainloader command when validation fails
    - 0101-relocator-Protect-grub_relocator_alloc_chunk_addr-in.patch:
      Protect grub_relocator_alloc_chunk_addr input arguments against
      integer overflow / underflow
    - 0102-relocator-Protect-grub_relocator_alloc_chunk_align-m.patch:
      Protect grub_relocator_alloc_chunk_align max_addr argument against
      integer underflow
    - 0103-relocator-Fix-grub_relocator_alloc_chunk_align-top-m.patch: Fix
      grub_relocator_alloc_chunk_align top memory allocation
    - 0104-linux-loader-avoid-overflow-on-initrd-size-calculati.patch:
      Avoid overflow on initrd size calculation
  * debian/patches/linuxefi_disable_sb_fallback.patch: Disallow unsigned
    kernels if UEFI Secure Boot is enabled.  If UEFI Secure Boot is enabled
    and kernel signature verification fails, do not boot the kernel. Patch
    from Linn Crosetto. (LP: #1401532)
  * ubuntu-Make-the-linux-command-in-EFI-grub-always-try.patch:
    - Make the linux command in EFI grub always try EFI handover

  [ Dimitri John Ledkov ]
  * SECURITY UPDATE: Grub does not enforce kernel signature validation
    when the shim protocol isn't present.
    - 0097-linuxefi-fail-kernel-validation-without-shim-protoco.patch:
      Fail kernel validation if the shim protocol isn't available
    - CVE-2020-15705

 -- Chris Coulson <chris.coulson@xxxxxxxxxxxxx>  Mon, 20 Jul 2020
21:28:33 +0100

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

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-10713

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-14308

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-14309

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-14310

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-14311

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-15705

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-15706

** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-15707

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Matching subscriptions: Ubuntu 16.04 Bugs
https://bugs.launchpad.net/bugs/1401532

Title:
  GRUB's Secure Boot implementation loads unsigned kernel without
  warning

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2-signed package in Ubuntu:
  Fix Released
Status in grub2 source package in Trusty:
  Fix Released
Status in grub2-signed source package in Trusty:
  Fix Released
Status in grub2 source package in Xenial:
  Fix Released
Status in grub2-signed source package in Xenial:
  In Progress
Status in grub2 source package in Bionic:
  Fix Released
Status in grub2-signed source package in Bionic:
  Fix Released

Bug description:
  [Rationale]
  GRUB should help us enforce that in UEFI mode, only signed kernels are loaded. It should not silently fall back to loading unsigned kernels.

  [Impact]
  All our users booting in UEFI; on all supported releases.

  [Test cases]

  = grub2 =

  Booting unsigned kernels:
  1) Try to boot a custom kernel
  2) Verify that the kernel will not be loaded by grub (you should see an error message about the signature)

  Booting signed kernels:
  1) Try to boot an official signed kernel (from -release or -updates)
  2) Verify that the system boots normally and no warnings are shown about signature.

  
  [Regression Potential]
  Any failure to boot presenting as a failure to load the kernel from within grub, with an "invalid signature" type error message or not, should be investigated as a potential regression of this stable update.

  ---

  Me and some other students have conducted some various experiments on
  Secure Boot enabled machines. The main focus of the tests was to
  circumvent Secure Boot and load unsigned kernels or kernels that have
  been signed with other keys.

  On your SecureBoot (https://wiki.ubuntu.com/SecurityTeam/SecureBoot)
  it is outlined that GRUB will boot unsigned kernels when the kernel is
  unsigned. During one of our experiments it seemed that this statement
  was true and that GRUB loads unsigned kernels as described on your
  page. We understand that for various reasons GRUB should still support
  the use-case when an unsigned kernel must be loaded, but with the
  current approach the user isn't aware if there is a whole chain of
  trust. For example, it could still be possible to load some malware
  before it boots the Operating System itself (bootkits). One of the
  many reasons that Secure Boot has been developed is to protect the
  user from these kind of attacks.

  With the current approach the purpose of Secure Boot is somewhat
  defeated, and the user doesn't know if the whole chain has been
  verified or not. It could easily be the case that an unsigned kernel
  has been loaded by Ubuntu without the user noticing. From our point of
  view, a better approach would be to inform the user that an unsigned
  kernel will be loaded and that the user can make a choice if he/she
  wants to proceed. The default action could be to accept the option,
  remember the user's option and sometimes remind the user of the fact
  that it is loading an unsigned kernel.

  This problem is of course related to GRUB itself and not to Ubuntu
  itself. The reason for filing this bug and informing the SecurityTeam
  of Ubuntu is to ask for their opinions and what your point of view is
  on the current approach and to see if other users classify this as a
  "bug".

  GRUB2 versions: grub-2.02~beta2, 1.34.1+2.02~beta2-9ubuntu1
  Ubuntu version: Trusty (will also affect newer and older versions, GRUB specific problem)

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