1) checking that reproducer still fails sudo qemu-system-x86_64 -kernel ./vmlinuz-5.4.0-64-generic -initrd ./initrd-pad4-5.4.0-64-generic -append 'break=top quiet console=ttyS0' -m 2G -nograt
[ 3.581106] Initramfs unpacking failed: Decoding failed Spawning shell within the initramfs BusyBox v1.30.1 (Ubuntu 1:1.30.1-4ubuntu6.3) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs) cat /test-file cat: can't open '/test-file': No such file or directory (initramfs) uname -a Linux (none) 5.4.0-64-generic #72-Ubuntu SMP Fri Jan 15 10:27:54 UTC 2021 x86_64 GNU/Linux (initramfs) As expected, error message shown and file from second initrd is not accessible 2) checking that #65 ABI build of v5.4 is good Verifying v5.4 using a custom test case: sudo qemu-system-x86_64 -kernel ./vmlinuz-5.4.0-65-generic -initrd ./initrd-pad4-5.4.0-65-generic -append 'break=top quiet console=ttyS0' -m 2G -nograt Spawning shell within the initramfs BusyBox v1.30.1 (Ubuntu 1:1.30.1-4ubuntu6.3) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs) cat /test-file second (initramfs) uname -a Linux (none) 5.4.0-65-generic #73-Ubuntu SMP Mon Jan 18 17:25:17 UTC 2021 x86_64 GNU/Linux (initramfs) QEMU 5.0.0 monitor - type 'help' for more information (qemu) quit All is good. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to initramfs-tools in Ubuntu. https://bugs.launchpad.net/bugs/1835660 Title: initramfs unpacking failed Status in OEM Priority Project: New Status in grub2 package in Ubuntu: Invalid Status in initramfs-tools package in Ubuntu: Invalid Status in linux package in Ubuntu: Confirmed Status in grub2 source package in Focal: Invalid Status in initramfs-tools source package in Focal: Invalid Status in linux source package in Focal: Fix Committed Status in grub2 source package in Groovy: Invalid Status in initramfs-tools source package in Groovy: Invalid Status in linux source package in Groovy: Fix Committed Status in grub2 source package in Hirsute: Invalid Status in initramfs-tools source package in Hirsute: Invalid Status in linux source package in Hirsute: Confirmed Bug description: "initramfs unpacking failed: Decoding failed", message appears on boot up. If I "update-initramfs" using gzip instead of lz, then boot up passes without decoding failed message. --- However, we currently believe that the decoding error reported in dmesg is actually harmless and has no impact on usability on the system. Switching from lz4 to gzip compression, simply papers over the warning, without any benefits, and slows down boot. Kernel should be fixed to correctly parse lz4 compressed initrds, or at least lower the warning, to not be user visible as an error. [Impact] * Decoding failure messages in dmsg with a single lz4 initrd * Multiple lz4 compressed initrds cannot be decompressed by kernel, when loaded by grub * Multiple lz4 compressed initrds cannot be decompressed by kernel, when there is padding between them [Test Case] * Create empty padding with $ dd if=/dev/zero of=pad4 bs=1 count=4 * Create an lz4 compressed initrd with a single test-file in it with some content. I.e. echo "second-initrd" > test-file, and then pack that with cpio hewc owned by root & lz4 -l. * Create a combined padded initrd of stock initrd, pad4, and the test-marker initrd created above. * Boot above with "break=top" kernel command line. * With broken kernels, there should be dmesg error message that decoding failed, and one will observe that /test-file does not exist in the shell. * With fixed kernel, /test-file in the initrd shell should exist, and should have the expected content "second-initrd". * The alignment and padding in the above test case depends on the size of the first initrd => if a given padded initrd does not reproduce the problem, try varying the size of the first initrd or that of the padding between 0..4. [Where problems could occur] * This changes compatible lz4 decompressor in the kernel, which can also be used by other kernel modules such as cryptography, squashfs, zram, f2fs, comprssed kernel image, pstore. For example, previously rejected files with "bogus" length and extra padding may now be accepted, whereas they were previously getting rejected by the decompressor. * Ideally kernel should switch to the stable lz4 format which has better specification of end of stream. To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1835660/+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
