Bug#966575: Security update can break grub - grub_calloc not found

[Steve McIntyre]

Hi Geoff,

On Fri, Jul 31, 2020 at 11:54:20AM +0100, Geoff Gibbs wrote:
>apt update
>apt full-upgrade
>
>grub upgrades
>
>from 2.02+dfsg1-20
>to 2.02+dfsg1-20+deb10u1
>
>no errors were spotted.
>
>When rebooted :-
>
>symbol grub_calloc not found
>Entering rescue mode
>grub rescue>
>
>
>I had to boot off a memory stick and then :-
>
>sudo -i
>mount /dev/sda5 /mnt
>grub-install --boot-directory=/mnt /dev/sda
>reboot
>
>This worked and the system now boots.
>
>/boot is the only ext type file system, the others are all handled by LVM

I'm guessing - do you have multiple disks on your system? If so, try
"grub-install <disk>" on each of the bootable disks and that should
fix your problem.

I think we need a proper fix for this in the longer term, but that's
not going to happen overnight.

-- 
Steve McIntyre, Cambridge, UK.                                steve at einval.com
You lock the door
And throw away the key
There's someone in my head but it's not me