[Bug 518582] Re: mount ext fileystem fails, booting fails, blkid produces no output

[Kees Cook]

I cannot reproduce this with a simple loop-back filesystem:

sudo -s
cd /tmp
dd if=/dev/zero of=test.ext4 bs=1 count=1 seek=1G
mkfs.ext4 -F test.ext4
mkdir -p /mnt/test
mount -o loop text.ext4 /mnt/test
echo $(seq $(hexdump -s 0x410 -n 2 -e '"%d\n"' test.ext4) - 9336 ) | (cd /mnt/test; xargs touch)
umount /mnt/test


$ blkid -p text.ext4
test.ext4: UUID="e6c2eb3d-91ca-42bd-8f09-ff118c9f47c1" TYPE="ext4" 
$ hexdump -s 0x410 -n 2 -e '"%d\n"' test.ext4
9336

In reading the blkid source, I think the minix filesystem superblock
magic is located at 0x110 not 0x410.  However, this bug shows blkid
reading 0x110 ("minix: magic sboff=16, kboff=1") kboff=1 == 0x100,
sboff=16 == 0x10

-- 
mount ext fileystem fails, booting fails, blkid produces no output
https://bugs.launchpad.net/bugs/518582
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