[Bug 1330963] [NEW] grub-probe: double free or corruption in some rare cases

[Vladimir Smirnov]

Public bug reported:

There is small bug in grub2 in trusty, that causing grub-probe to fail in some rare cases.
I've got system with follwing scheme:
GPT (4 HDD): 
1) 128MB Free space, bios_boot flag 
2) MDADM RAID10, /boot, ext3
3) MDADM RAID10, LVM vg0 (for /, /home, etc) 
4) MDADM RAID10, LVM vg1 (data partitions).

In this case grub fails with:
glibc detected *** ./grub-probe: double free or corruption (fasttop): 0x0000000000838760 ***

Cause of this behavior is grub-core/disk/diskfilter.c:886.

I've also filed a bug upstream: http://savannah.gnu.org/bugs/?41582
but it's still not closed and bug is present in Ubuntu 14.04.

I'm attaching my vision of fixing this bug here. Thoguh, there maybe a
better way to fix this.

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New

** Patch added: "0001-Fix-double-free-when-using-LVM.patch"
   https://bugs.launchpad.net/bugs/1330963/+attachment/4133236/+files/0001-Fix-double-free-when-using-LVM.patch

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https://bugs.launchpad.net/bugs/1330963

Title:
  grub-probe: double free or corruption in some rare cases

Status in “grub2” package in Ubuntu:
  New

Bug description:
  There is small bug in grub2 in trusty, that causing grub-probe to fail in some rare cases.
  I've got system with follwing scheme:
  GPT (4 HDD): 
  1) 128MB Free space, bios_boot flag 
  2) MDADM RAID10, /boot, ext3
  3) MDADM RAID10, LVM vg0 (for /, /home, etc) 
  4) MDADM RAID10, LVM vg1 (data partitions).

  In this case grub fails with:
  glibc detected *** ./grub-probe: double free or corruption (fasttop): 0x0000000000838760 ***

  Cause of this behavior is grub-core/disk/diskfilter.c:886.

  I've also filed a bug upstream: http://savannah.gnu.org/bugs/?41582
  but it's still not closed and bug is present in Ubuntu 14.04.

  I'm attaching my vision of fixing this bug here. Thoguh, there maybe a
  better way to fix this.

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