Bug#959425: loopback command hangs in 2.04 under UEFI

[Alkis Georgopoulos]

Source: grub2
Version: 2.04-7
Severity: important

Hi, if I boot with grubx64.efi and run the following command:
loopback loop some.iso

...it hangs in 2.04 under UEFI, while it worked fine up to 2.02.
This affects Debian and Ubuntu, but not Fedora.
BIOS mode isn't affected.

I tested with grubx64.efi from the following packages:

BAD: 
http://ftp.us.debian.org/debian/pool/main/g/grub2/grub-efi-amd64-bin_2.04-7_amd64.deb

BAD: 
https://launchpad.net/ubuntu/+source/grub2-signed/1.117/+build/17277557/+files/grub-efi-amd64-signed_1.117+2.04-1ubuntu1_amd64.deb

GOOD: 
https://launchpad.net/ubuntu/+source/grub2-signed/1.116/+build/17166212/+files/grub-efi-amd64-signed_1.116+2.02+dfsg1-12ubuntu3_amd64.deb

GOOD: 
https://kojipkgs.fedoraproject.org//packages/grub2/2.04/15.fc33/x86_64/grub2-efi-x64-2.04-15.fc33.x86_64.rpm

Related Ubuntu bug report:
https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1851311

Thank you.