Sorry, forgot to reply to list as well, resending for completeness.

On Mon, Mar 28, 2016 at 08:19:12AM -0400, Phil Turmel wrote:

On 03/28/2016 06:31 AM, Étienne Buira wrote:

../..

quoted

After printking the values for rdev->new_data_offset and
rdev->data_offset in the
if (rdev->new_data_offset != rdev->data_offset) { ...
block of super_1_sync, i found that new_data_offset (252928 in my case)
where smaller than data_offset (258048), thus, the substraction to
compute sb->new_data_offset yielded an insanely high value.

Modern mdadm and kernels avoid the use of backup files by adjusting the
data offset.  The lowered offset you see is normal.

I suspect the grsecurity kernels haven't kept up with this.  If you can
reproduce a problem with a vanilla kernel, please report back here.
Otherwise you'll have to report to your kernel provider.

Phil

Hi,

Thank you for the answer.

I tried to reproduce the case with vanilla 4.4.6, but couldn't enter the
above said 'if', so i'm giving up on this topic.

However, i'm still surprised that sb->new_offset gets assigned a
'negative' (well, high, because it is computed unsigned) value.

Regards.

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