Public bug reported: 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. ** Affects: util-linux (Ubuntu) Importance: Undecided Status: Fix Released ** Affects: util-linux (Ubuntu Xenial) Importance: Medium Assignee: Mauricio Faria de Oliveira (mfo) Status: In Progress ** Also affects: util-linux (Ubuntu Xenial) Importance: Undecided Status: New ** Changed in: util-linux (Ubuntu) Status: New => Fix Released ** Changed in: util-linux (Ubuntu Xenial) Status: New => In Progress ** Changed in: util-linux (Ubuntu Xenial) Assignee: (unassigned) => Mauricio Faria de Oliveira (mfo) ** Changed in: util-linux (Ubuntu Xenial) Importance: Undecided => Medium -- 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 : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
