Re: [Qemu-devel] [PATCH] qcow2: Unset zero_beyond_eof in save_vmstate

[Max Reitz]

On 2013-10-21 22:37, Eric Blake wrote:
> On 10/20/2013 08:52 PM, Max Reitz wrote:
> > Saving the VM state is done using bdrv_pwrite. This function may perform
> > a read-modify-write, which in this case results in data being read from
> > beyond the end of the virtual disk. Since we are actually trying to
> > access an area which is not a part of the virtual disk, zero_beyond_eof
> > has to be set to false before performing the partial write, otherwise
> > the VM state may become corrupted.
> >
> > Signed-off-by: Max Reitz <address@hidden>
> > ---
> > Follow-up to (depends on):
> >   - qcow2: Restore total_sectors value in save_vmstate
> Reviewed-by: Eric Blake <address@hidden>
>
> Do you have test cases that demonstrate the corruption pre-patch?

Okay, so it is possible to test for this after all; I've just sent a 
follow-up adding such a test. Thanks for pointing that out. ;-)

Max