** Summary changed: - grub 2.06 prob fat fs fail. + FAT filesystem probing fails if a file's timestamp exceeds 2038
** Description changed: - I found this issue on Ubuntu 22.04.5 LTS, but it's a general issue for grub-2.06. - This is my setup information： - nvme0n1 - ├─nvme0n1p1 vfat FAT32 EFI0 5282-D345 40.6M 17% /boot/efi - └─nvme0n1p2 ext4 1.0 OS0 bdfcdb95-b1c7-42ea-b1b8-69c20099586e 105.6G 4% / - The first partition is /dev/nvme0n1p1, FAT format. - The grub prefix environment value default be set: - prefix=(hd0,gpt1)/EFI/ubuntu # read grub at /boot/efi/EFI/ubuntu/grub.cfg. + [Impact] + If any file's timestamp under `/boot/efi` exceeds 2038, the FAT filesystem probe will fail, and the system will drop into the GRUB shell. - Grub will first probe the /dev/nvme0n1p1, which is the FAT format. When - trying FAT fs, the mount is successful, but there is a check that if any - files under the mount patch(/boot/efi) timestamp exceeds 2038, probe - will fail, and try next type FS(for example, ext2...). Ultimately, the - probe will fail and can not read the grub.cfg and show the grub menu, - then enter the grub cmdline. + [Fix] + There is an upstream patch that fixes this issue: + https://git.savannah.gnu.org/cgit/grub.git/commit/grub-core/fs?id=e43f3d93b28cce852c110c7a8e40d8311bcd8bb1 - It's easy to reproduce: - touch -d "2038-02-20" /boot/efi/EFI - reboot. # After reboot, enter the grub cmdline. + [Test Plan] + 1. Change the timestamp of a directory under /boot/efi to exceed 2038: + touch -d "2038-02-27" /boot/efi/EFI + 2. Reboot, and the system will be entered into the grub shell. - Can mannel boot the setup success: - set prefix=(hd0,gpt2)/boot/grub # set the "grub.cfg" on the second partition, it's ext2 format. The path is: "/boot/grub/grub.cfg". Actually "/boot/efi/EFI/ubuntu/grub.cfg" redirected to it. - insmod linux - insmod normal - normal # Boot linux success. - - There already is a fix in the master branch: e43f3d93b fs/fat: Don't error when mtime is 0. - I have tested it, and it works. We need to include this patch in the latest Ubuntu grub-2.06 code. + [Where problems could occur] + The patch simply bypasses the error logic when the modification time is zero in FAT. + There should be no regression unless the FAT filesystem is unable to handle such scenarios. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2098641 Title: FAT filesystem probing fails if a file's timestamp exceeds 2038 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/2098641/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
