Control: retitle -1 misdetects FAT-overwritten-with-ext2 as FAT Control: severity -1 important
On Mon, May 20, 2013 at 07:55:19PM +0100, Jim Hague wrote: > Package: grub-pc > Version: 2.00-14 > Severity: critical > Justification: breaks the whole system > > After update from 1.99-27 on my i386 laptop, it failed to boot, stopping at > the > grub-rescue prompt. > > grub-rescue could see (hd0), (hd0,msdos1) and (hd0,msdos2). (hd0,msdos2) is a > LVM partition containing the root filesystem. (hd0,msdos1) is the boot > partition containing an ext2 filesystem. All prefixes were correct, but grub > reported it could not find /grub/i386-pc/normal.mod. This was apparently > because Grub could not find any files on the partition. > > grub-rescue>ls (hd0,msdos1) > > grub-rescue> > > I used boot-repair to fsck the boot partition (clean), and to purge and re- > install grub, configuring as before boot sda, boot partition sda1. On > rebooting, no change. > > I then tried saving the content of the boot partition, re-creating the boot > partition filesystem (using mkfs.ext3), copying the files back and re-running > update-grub and grub-install. The machine booted correctly, so I therefore > infer something about my /boot ext2 filesystem was causing it to be misread by > 2.00-14. > > A copy of the offening boot partition (saved with 'dd if=/dev/sda1 of=<file> > bs=1M') is at http://www.lunch.org.uk/grub2-empty-partition.bz2. This is a pretty specialised (hence the severity downgrade), but interesting, corner case. It appears that the partition in question used to be a FAT filesystem (specifically, a Dell Utility partition). It has been overwritten sufficiently that the fstype magic has been overwritten: 00000000 eb 54 90 00 65 6c 6c 20 38 2e 30 00 02 08 01 00 |.T..ell 8.0.....| 00000010 02 00 02 00 00 f8 86 00 3f 00 ff 00 3f 00 00 00 |........?...?...| 00000020 92 2a 04 00 80 00 29 1c 0a d9 07 44 65 6c 6c 55 |.*....)....DellU| 00000030 74 69 6c 69 74 79 00 41 54 31 36 20 20 20 10 00 |tility.AT16 ..| This means that blkid no longer detects it as FAT, but unfortunately GRUB does ever since this commit: revno: 1855.125.850 committer: Vladimir 'phcoder' Serbinenko <phco...@gmail.com> branch nick: grub timestamp: Tue 2012-01-31 23:26:07 +0100 message: * grub-core/fs/fat.c (grub_fat_mount) [!MODE_EXFAT]: Remove fstype check as some mkfs implementations omit it. Vladimir, could you elaborate on this? Which mkfs implementations were involved here? It seems questionable to me for GRUB to be quite this liberal. Perhaps we can restore its previous strictness somehow without breaking the filesystems that Vladimir ran into? Thanks, -- Colin Watson [cjwat...@debian.org] _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
