[dm-devel] dm-verity: Verification fails but do not see Input/Output Error on read
Mikulas Patocka
mpatocka at redhat.com
Thu Aug 15 00:23:08 UTC 2013
On Tue, 13 Aug 2013, Chaitra Bhat wrote:
> Hi Mikulas,
>
> I figured out what was happening - but I would need your help to explain
> these behaviours please :)
>
> Case I - Format the hash device, verify and create the dm-verity target.
> Then modify data in the underlying data-device using dd. Read back the
> data from the modified location from the verity-device.
>
> Result: Verify fails but 'NO' I/O error reported when reading back from
> the location using dd.
So, create a script that results in this scenario of not reporting I/O
error and send it to us.
Mikulas
> Case II - Format the hash device, verify and create the dm-verity target
> device. Remove the verity target, then modify the data in the
> data-device using dd. Load the verity target and read-back the data from
> the verity-device from the modified location.
>
> Result: Verify fails and also get I/O error on reading that location
> using dd.
>
> My understanding was that the verity-device could be created and mounted
> and then if the underlying data was corrupted somehow, then a read of
> invalid data from that corrupted location will return -EIO.
>
> Chaitra
>
> PS: I was following the examples in the verity-compat-test script.
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