[bug #61620] Grub2 fails to detect LVM volumes with: error: disk `lvmid/*/*' not found

[Rogier]

URL:
  <https://savannah.gnu.org/bugs/?61620>

                 Summary: Grub2 fails to detect LVM volumes with: error: disk
`lvmid/*/*' not found
                 Project: GNU GRUB
            Submitted by: rogier777
            Submitted on: Sat 04 Dec 2021 10:44:41 PM UTC
                Category: Disk &amp; Partition
                Severity: Major
                Priority: 5 - Normal
              Item Group: Software Error
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: 
                 Release: Git master
         Discussion Lock: Any
         Reproducibility: Every Time
         Planned Release: None

    _______________________________________________________

Details:

See also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=987008

When handling a regular LVM volume, Grub can fail with the message:
error: disk `lvmid/******-****-****-****-****-****-
******/******-****-****-****-****-****-******' not found.

If the condition which triggers this exists, grub-probe will report the error
mentioned above. Similarly, the grub boot code will fail to detect LVM
volumes, resulting in a failure to boot off of LVM disks/partitions. The
condition can be created on any LVM VG by an LVM configuration change, so any
system with /boot on LVM can become unbootable at 'any' time (after any LVM
configuration change).

==== Cause ===
The problem is caused by an incorrect computation of mda_end in lvm.c, when
the metadata area wraps around.
Patch included below.

=== How to reproduce ===
Run the (first) attached script (as root!). On my system, it reliably fails at
lv81. If not, the second script can be run until the error occurs. It requires
a parameter indicating the number of iterations.
WARNING: Don't run the scripts if you don't understand what they do.
WARNING 2: The name of the loop device may have to be changed before running
the script!

=== Patch ===
I hereby release this patch to the public domain, to (hopefully) avoid any
copyright assignment problems.
---------------------------------------------------
Index: grub2-2.02+dfsg1/grub-core/disk/lvm.c
===================================================================
--- grub2-2.02+dfsg1.orig/grub-core/disk/lvm.c
+++ grub2-2.02+dfsg1/grub-core/disk/lvm.c
@@ -253,7 +253,7 @@ error_parsing_metadata:

   p = q = (char *)ptr;

-  if (grub_add ((grub_size_t)metadatabuf, (grub_size_t)mda_size, &ptr))
+  if (grub_add (ptr, (grub_size_t)grub_le_to_cpu64 (rlocn->size), &ptr))
     goto error_parsing_metadata;

   mda_end = (char *)ptr;
----------------------------------------------------



    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Sat 04 Dec 2021 10:44:41 PM UTC  Name: setup-report  Size: 729B   By:
rogier777

<http://savannah.gnu.org/bugs/download.php?file_id=52432>
-------------------------------------------------------
Date: Sat 04 Dec 2021 10:44:41 PM UTC  Name: test-grub  Size: 414B   By:
rogier777

<http://savannah.gnu.org/bugs/download.php?file_id=52433>

    _______________________________________________________

Reply to this item at:

  <https://savannah.gnu.org/bugs/?61620>

_______________________________________________
  Message sent via Savannah
  https://savannah.gnu.org/