[Bug 1507443] Re: intel-microcode seems to result in an invalid initrd
[Expired for intel-microcode (Ubuntu) because there has been no activity for 60 days.] ** Changed in: intel-microcode (Ubuntu) Status: Incomplete => Expired -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1507443 Title: intel-microcode seems to result in an invalid initrd To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/intel-microcode/+bug/1507443/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1507443] Re: intel-microcode seems to result in an invalid initrd
The gzipped CPIO archive at file position 0x2c00 is valid: $ dd if=/tmp/initrd.img-4.2.0-16-generic.bak of=/tmp/initramfs.bin.gz bs=256 skip=44 $ zcat /tmp/initramfs.bin.gz | cpio -t -i >/dev/null 176985 blocks And the first uncompressed CPIO archive at file position 0 is also valid: $ cat /tmp/initrd.img-4.2.0-16-generic.bak | cpio -t -i kernel kernel/x86 kernel/x86/microcode kernel/x86/microcode/GenuineIntel.bin 22 blocks The padding between the two initramfs is a sequence of zeros, and it is aligned to a block/record size of 1024, which is one of the typical block sizes for CPIO archives (cpio block size only affects padding). The heuristics initramfs-tools "lsinitramfs" uses to locate the next initramfs are incomplete (it does not skip over the padding at the end of each initramfs) and causes zcat to crash (which is likely a bug in zcat itself): $ lsinitramfs /tmp/initrd.img-4.2.0-16-generic.bak /tmp/initrd.img-4.2.0-16-generic.bak kernel kernel/x86 kernel/x86/microcode kernel/x86/microcode/GenuineIntel.bin *** Error in `zcat': double free or corruption (!prev): 0x021efdb0 *** I will check if something changed in the early initramfs loaders from kernel 4.1 to 4.2, but this is not likely to be the root cause of the problem. Can you still reproduce this bug with up-to-date kernels (i.e. please test against 4.1.17 and 4.3.5 or 4.4.1) ? -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1507443 Title: intel-microcode seems to result in an invalid initrd To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/intel-microcode/+bug/1507443/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
[Bug 1507443] Re: intel-microcode seems to result in an invalid initrd
Ok, there are no changes between 4.1 and 4.2 (actually, between 4.1 and 4.2.8) re. either the earlycpio or the initramfs loaders. So, the problem lies elsewhere. That said, since I bothered to research this: EARLY cpio loader (lib/earlycpio.c, loads the microcode data): always skips zero DWORDs (4 bytes) before any cpio header, so it will just concatenate every non-compressed cpio archive and skip any dword-aligned zero padding before, after, or between cpio archive headers. There is one header per file/directory inside the cpio archive. Note: the early cpio loader does not care for subdirectories, it can find data by the whole path, and that's how microcode is loaded. This means the cpio archive with microcode does not need to have any of the subdirectories inside, it doesn't matter to the kernel. LATE cpio loader (init/initramfs.c, loads the real initramfs): 1. Skips any zero bytes before the compressed or uncompressed data (thus, skips any padding between cpio archives). 2. Unpacks any compressed or uncompressed cpio archive it finds, concatenating the contents (thus, it *will* also unpack the microcode in the first cpio archive, and this file will be available inside the initramfs). 3. It *depends* on subdirectories being created *first* before any files inside them. If this is not done, it will ignore the file. 4. It does NOT skip inital zero-padding on the *decompressed* data (i.e. if you compress a cpio archive, it must not have any initial zero padding). 5. It skips any zero padding at the end (compressed or not), but the zeros must *end* at a DWORD boundary. So, we need more data to debug this. Because the kernel should have been able to read and unpack that initramfs just fine. The boot log (with the exact error message) or a better description of exactly where (and how) things went wrong during the boot would help. ** Changed in: intel-microcode (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1507443 Title: intel-microcode seems to result in an invalid initrd To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/intel-microcode/+bug/1507443/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
