Re: [bug] incorrect GPT entry validation?

[Karel Zak <kzak@redhat.com>]

On Sat, Nov 03, 2012 at 02:35:11PM -0400, Dave Reisner wrote:
> Hi,
> 
> A user reported problems with libblkid incorrectly reporting (or not
> reporting) tags for some partitions on a GPT formatted disk. I was able
> to reproduce it:
> 
> - created a 10G disk on a VM
> - initialized it with GPT (using gdisk), created 5 entries
> - formatted each of them with ext4
> 
> blkid correctly reads the first 2 entries on the disk, but then starts
> reporting corrupted GPT entries (seen via LIBBLKID_DEBUG=0xffff):
> 
> https://dev.archlinux.org/~dreisner/blkid_bad.txt

It would be nice to have the debug output.

Please, send me begin of the device:

    # dd if=/dev/vdd of=img count=1 bs=1Mib
    # gzip -9 img

> It's interesting to note that blkid will _always_ read 2 entries before
> reporting corruption, i.e.

Hmm... sounds like in-memory buffer corruption libblkid caches the
data from the device).

> # blkid -c /dev/null /dev/vdd{4,5,2}

Are you able to reproduce the bug by "blkid -p -o udev" ?

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com