GRUB may execute the kernel w/ dirty instruction cache on arm64

[dann frazier]

[Impact]
Similar to bug 1987541, where shim may execute GRUB w/ polluted instruction cache, GRUB itself also fails to flush the instruction cache for the kernel memory before starting it. This is believed to be the source of some rare crashes seen executing instructions in the kernel EFI stub.

[Test Case]
Put an arm64 server in a reboot loop and watch for a crash (synchronous exception abort) after GRUB has started executing the kernel.

[Fix]
https://github.com/rhboot/grub2/commit/4e9020a937a30873fa63ba34e16c1e6fb7e7b718

[What could go wrong]
The only risk I can identify is possibly-measurable performance impact to booting the kernel.

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub2-unsigned - 2.06-2ubuntu12

---------------
grub2-unsigned (2.06-2ubuntu12) kinetic; urgency=medium

  * ubuntu-zfs-enhance-support.patch: Fix missing lines (LP: #1990143)
  * Source package generated from src:grub2 using make -f ./debian/rules
    generate-grub2-unsigned

 -- Julian Andres Klode <email address hidden> Mon, 19 Sep 2022 16:00:47 +0200

[dann frazier (dannf)]

The fix has now been merged into the rhboot tree: https://github.com/rhboot/grub2/commit/4e9020a937a30873fa63ba34e16c1e6fb7e7b718

[Steve Langasek (vorlon)]

Hello dann, or anyone else affected,

Accepted grub2-unsigned into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/grub2-unsigned/2.04-1ubuntu47.5 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[dann frazier (dannf)]

= verification =
I've rebooted a BlueField 2 device several times with this update. I've neither seen a hang nor any sign of regression.

ubuntu@localhost:~$ dpkg -l | grep grub
ii grub-common 2.04-1ubuntu26.16 arm64 GRand Unified Bootloader (common files)
ii grub-efi-arm64 2.04-1ubuntu47.5 arm64 GRand Unified Bootloader, version 2 (ARM64 UEFI version)
ii grub-efi-arm64-bin 2.04-1ubuntu47.5 arm64 GRand Unified Bootloader, version 2 (ARM64 UEFI modules)
ii grub-efi-arm64-signed 1.173.4+2.04-1ubuntu47.5 arm64 GRand Unified Bootloader, version 2 (EFI-ARM64 version, signed)
ii grub2-common 2.04-1ubuntu26.16 arm64 GRand Unified Bootloader (common files for version 2)

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub2-unsigned - 2.04-1ubuntu47.5

---------------
grub2-unsigned (2.04-1ubuntu47.5) focal; urgency=medium

  [ Chris Coulson ]
  * SECURITY UPDATE: Fix out of bounds writes due specially crafted fonts.
    - add debian/patches/font-Fix-several-integer-overflows-in-grub_font_construct.patch
    - add debian/patches/font-Fix-an-integer-underflow-in-blit_comb.patch
    - CVE-2022-2601, CVE-2022-3775
    - LP: #1996950
  * Fix various issues as a result of fuzzing, static analysis and code
    review:
    - add debian/patches/font-Reject-glyphs-exceeds-font-max_glyph_width-or-font-m.patch
    - add debian/patches/font-Fix-size-overflow-in-grub_font_get_glyph_internal.patch
    - add debian/patchces/font-Remove-grub_font_dup_glyph.patch
    - add debian/patches/font-Fix-integer-overflow-in-ensure_comb_space.patch
    - add debian/patches/font-Fix-integer-overflow-in-BMP-index.patch
    - add debian/patches/font-Fix-integer-underflow-in-binary-search-of-char-index.patch
    - add debian/patches/fbutil-Fix-integer-overflow.patch
    - add debian/patches/font-Harden-grub_font_blit_glyph-and-grub_font_blit_glyph.patch
    - add debian/patches/font-Assign-null_font-to-glyphs-in-ascii_font_glyph.patch
    - add debian/patches/normal-charset-Fix-an-integer-overflow-in-grub_unicode_ag.patch
  * Forbid loading of external fonts when secure boot is enabled:
    - add debian/patches/font-Forbid-loading-of-font-files-when-secure-boot-is-ena.patch
  * Bundle unicode.pf2 in a squashfs memdisk attached to the signed EFI binary
    - update debian/control
    - update debian/build-efi-image
    - add debian/patches/font-Try-opening-fonts-from-the-bundled-memdisk.patch
  * Fix the squashfs tests during the build
    - remove debian/patches/ubuntu-fix-reproducible-squashfs-test.patch
    - add debian/patches/tests-Explicitly-unset-SOURCE_DATE_EPOCH-before-running-f.patch
  * Bump SBAT generation:
    - update debian/sbat.ubuntu.csv.in
  * Make grub-efi-{amd64,arm64} depend on grub2-common 2.02~beta2-36ubuntu3.33
    in xenial and 2.02-2ubuntu8.25 in bionic to fix LP: #1995751 (thanks
    Julian Klode for the base-files hack to make a single binary be able to
    depend on 2 different versions of the same package)

  [ dann frazier ]
  * linuxefi: Invalidate i-cache before starting the kernel (LP: #1987924)
    - d/p/linuxefi-Invalidate-i-cache-before-starting-the-kern.patch

  [ Chris Coulson ]
  * Source package generated from src:grub2 using make -f ./debian/rules
    generate-grub2-unsigned

 -- Chris Coulson <email address hidden> Thu, 17 Nov 2022 13:27:15 +0000

[Steve Langasek (vorlon)]

The verification of the Stable Release Update for grub2-unsigned has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub2-unsigned - 2.06-2ubuntu14

---------------
grub2-unsigned (2.06-2ubuntu14) kinetic; urgency=medium

  * SECURITY UPDATE: Fix out of bounds writes due specially crafted fonts.
    - add debian/patches/font-Fix-several-integer-overflows-in-grub_font_construct.patch
    - add debian/patches/font-Fix-an-integer-underflow-in-blit_comb.patch
    - CVE-2022-2601, CVE-2022-3775
    - LP: #1996950
  * Fix various issues as a result of fuzzing, static analysis and code
    review:
    - add debian/patches/font-Reject-glyphs-exceeds-font-max_glyph_width-or-font-m.patch
    - add debian/patches/font-Fix-size-overflow-in-grub_font_get_glyph_internal.patch
    - add debian/patchces/font-Remove-grub_font_dup_glyph.patch
    - add debian/patches/font-Fix-integer-overflow-in-ensure_comb_space.patch
    - add debian/patches/font-Fix-integer-overflow-in-BMP-index.patch
    - add debian/patches/font-Fix-integer-underflow-in-binary-search-of-char-index.patch
    - add debian/patches/fbutil-Fix-integer-overflow.patch
    - add debian/patches/font-Harden-grub_font_blit_glyph-and-grub_font_blit_glyph.patch
    - add debian/patches/font-Assign-null_font-to-glyphs-in-ascii_font_glyph.patch
    - add debian/patches/normal-charset-Fix-an-integer-overflow-in-grub_unicode_ag.patch
  * Enforce verification of fonts when secure boot is enabled:
    - add debian/patches/kern-efi-sb-Enforce-verification-of-font-files.patch
  * Bundle unicode.pf2 in a squashfs memdisk attached to the signed EFI binary
    - update debian/control
    - update debian/build-efi-image
    - add debian/patches/font-Try-opening-fonts-from-the-bundled-memdisk.patch
  * Fix LP: #1997006 - add support for performing measurements to RTMRs
    - add debian/patches/commands-efi-tpm-Refine-the-status-of-log-event.patch
    - add debian/patches/commands-efi-tpm-Use-grub_strcpy-instead-of-grub_memcpy.patch
    - add debian/patches/efi-tpm-Add-EFI_CC_MEASUREMENT_PROTOCOL-support.patch
  * Fix the squashfs tests during the build
    - remove debian/patches/ubuntu-fix-reproducible-squashfs-test.patch
    - add debian/patches/tests-Explicitly-unset-SOURCE_DATE_EPOCH-before-running-f.patch
  * Bump SBAT generation:
    - update debian/sbat.ubuntu.csv.in
  * Source package generated from src:grub2 using make -f ./debian/rules
    generate-grub2-unsigned

 -- Chris Coulson <email address hidden> Wed, 16 Nov 2022 14:40:42 +0000