I try to upgrade a Debian Bullseye but I get an anxious warning message :

 % sudo aptitude upgrade
Resolving dependencies...
The following NEW packages will be installed:
  linux-headers-5.10.0-18-amd64{a} linux-headers-5.10.0-18-common{a} linux-image-5.10.0-18-amd64{a}
The following packages will be REMOVED:
The following packages will be upgraded:
  avahi-autoipd avahi-daemon base-files bind9-dnsutils bind9-host bind9-libs chromium chromium-common chromium-sandbox clamav clamav-base clamav-freshclam cri-tools curl dpkg dpkg-dev
  fig2dev firefox-esr firefox-esr-l10n-fr fonts-opensymbol gir1.2-ayatanaappindicator3-0.1 gir1.2-gdkpixbuf-2.0 gir1.2-javascriptcoregtk-4.0 gir1.2-lokdocview-0.1 gir1.2-webkit2-4.0
  gping grub-common grub-pc grub-pc-bin grub2-common krb5-locales kubeadm kubectl kubelet kubernetes-cni libavahi-client3 libavahi-common-data libavahi-common3 libavahi-compat-libdnssd1
  libavahi-core7 libavahi-glib1 libayatana-appindicator1 libayatana-appindicator3-1 libc-bin libc-dev-bin libc-devtools libc-l10n libc6 libc6-dev libclamav9 libcurl3-gnutls libcurl4
  libdatetime-timezone-perl libdpkg-perl libexpat1 libexpat1-dev libgdk-pixbuf-2.0-0 libgdk-pixbuf-2.0-dev libgdk-pixbuf2.0-bin libgdk-pixbuf2.0-common libgssapi-krb5-2
  libhttp-daemon-perl libhttp-parser2.9 libjavascriptcoregtk-4.0-18 libjs-bootstrap4 libjuh-java libjurt-java libk5crypto3 libkrb5-3 libkrb5support0 liblibreoffice-java
  liblibreofficekitgtk libnss-myhostname libnss-systemd libpam-systemd libpcre2-16-0 libpcre2-32-0 libpcre2-8-0 libpcre2-dev libpcre2-posix2 libpoppler-cpp0v5 libpoppler-glib8
  libpoppler-qt5-1 libpoppler102 libpq5 libreoffice-base-core libreoffice-calc libreoffice-common libreoffice-core libreoffice-draw libreoffice-gnome libreoffice-gtk3
  libreoffice-help-common libreoffice-help-en-us libreoffice-help-fr libreoffice-impress libreoffice-l10n-fr libreoffice-math libreoffice-style-colibre libreoffice-style-elementary
  libreoffice-writer libreofficekit-data libridl-java libsystemd0 libudev1 libuno-cppu3 libuno-cppuhelpergcc3-3 libuno-purpenvhelpergcc3-3 libuno-sal3 libuno-salhelpergcc3-3
  libunoloader-java libwebkit2gtk-4.0-37 libxnvctrl0 libxslt1.1 linux-compiler-gcc-10-x86 linux-headers-amd64 linux-image-amd64 linux-kbuild-5.10 linux-libc-dev locales poppler-utils
  publicsuffix python3-uno systemd systemd-sysv systemd-timesyncd thunderbird tzdata udev uno-libs-private ure virtualbox virtualbox-dkms virtualbox-qt zlib1g zlib1g-dev
The following packages are RECOMMENDED but will NOT be installed:
  libnss-nis libnss-nisplus
136 packages upgraded, 3 newly installed, 1 to remove and 0 not upgraded.
Need to get 0 B/540 MB of archives. After unpacking 400 MB will be used.
Do you want to continue? [Y/n/?] y
Retrieving bug reports... Done
Parsing Found/Fixed information... Done
critical bugs of libc6 (2.31-13+deb11u3 -> 2.31-13+deb11u4) <Outstanding>
 b1 - #1019855 - Fwd: libc6: immediately crashes with SIGILL on 4th gen Intel Core CPUs (seems related to AVX2 instructions), bricking the whole system
grave bugs of grub-pc (2.04-20 -> 2.06-3~deb11u2) <Outstanding>
 b2 - #1019564 - (during upgrade) grub-install: warning: Attempting to install GRUB to a disk with multiple partition labels.  This is not supported yet..
 libc6(1 bug), grub-pc(1 bug)
Are you sure you want to install/upgrade the above packages? [Y/n/?/...]

So, what’s the matter with libc6 and grub-pc, is the problem as dangerous as apt tell? What concretely can happens? Can I by the way say “yes” and keep going?


1 Answer 1


You can see the bug details in the Debian BTS: 1019564 and 1019855.

The libc6 bug only affects fourth-generation Intel systems (Haswell), so if your CPU isn’t a Haswell CPU you can ignore it. There hasn’t been much feedback from the original reporter so it’s not clear how serious the bug actually is. For what it’s worth, my Haswell system is running fine with the upgraded libc6.

The grub-pc bug seems to be tied to a rather specific setup, you’re unlikely to run into it (I didn’t).

You’ll have to make up your own mind, but as far as I’m concerned it’s safe to press Y and upgrade the packages.

If you’re worried about these bugs, you can put the affected packages on hold and upgrade the rest of the upgradable packages.

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