with debug we could confirm that other fields in the backup superblock are invalid, such as the device size, which was not checked for not being a whole-disk device, and the bytes length, which is greater than the superblock structure size (8243 vs 1024).
so, the fix to check for the bytes field not being out-of-range resolves this case. primary superblock 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:77 :: entry 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:80 :: not sb or not magic backup superblock 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:77 :: entry 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:84 :: is_bak 1 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:85 :: is_wholedisk 0 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:86 :: sb->s_dev_size 3_472_328_296_366_616_623 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:87 :: pr->size 1_072_693_248 586: libblkid: LOWPROBE: nilfs2: nilfs_valid_sb:96 :: bytes 8243 586: libblkid: LOWPROBE: incorrect checksum for type nilfs2, got 56C7A81B, expected 2D2D206B 586: libblkid: LOWPROBE: assigning SBBADCSUM [superblocks] 586: libblkid: LOWPROBE: nilfs2: primary=0, backup=1 586: libblkid: LOWPROBE: nilfs2: primary=0, backup=1, swap=1 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to util-linux in Ubuntu. https://bugs.launchpad.net/bugs/1842437 Title: Xenial: libblkid: fix false-positive/misdetection of nilfs2 filesystem with udev Status in util-linux package in Ubuntu: Fix Released Status in util-linux source package in Xenial: In Progress Bug description: The nilfs filesystem has a backup superblock at the end of the device. If the magic number is coincidentally found at the right position and the filesystem is on a partition/not-wholedisk device, the only check left is for checksum verification, which is explicitly ignored in 'udev built-in blkid'. This causes blkid to detect one actually valid filesystem with a superblock at the beginning of the device (e.g., ext4), and then an invalid nilfs2 filesystem due to a coincidental magic number at the end of the device. And this causes blkid to break out of the safeprobe routine (which expects a single filesystem to be detected), and not print the UUIDs, thus not creating /dev/disk/by-uuid/ links which prevent mounting the partition by-uuid at boot time, causing emergency shell/boot failures. This upstream fix resolved the problem by introducing a check for the 'bytes' paramenters in the superblock, which is read from disk, and turns out to have an out-of-range value. - 'liblkid: Add length check in probe_nilfs2 before crc32' https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?id=ac681a310c32319423297544833932f4d689a7a2 $ git describe --contains ac681a310c32319423297544833932f4d689a7a2 v2.29-rc1~172 Xenial, which is v2.27.1-based, is the only release that needs it. Bionic is v2.31.1, so all post-Xenial supported releases have it. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/util-linux/+bug/1842437/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : firstname.lastname@example.org Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp