Re: [Qemu-devel] [PATCH v2 6/7] block/qcow2-refcount: fix out-of-file L1 entries to be zero

[Max Reitz <mreitz@redhat.com>]

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On 17.08.18 14:22, Vladimir Sementsov-Ogievskiy wrote:
> Zero out corrupted L1 table entry, which reference L2 table out of
> underlying file.
> Zero L1 table entry means that "the L2 table and all clusters described
> by this L2 table are unallocated."
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/qcow2-refcount.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)

Hm.  The specification actually says nothing about offsets being allowed
past the end of the file, and I don't think we ever use them (outside of
a very short period during image creation, where we point to refcount
structures beyond the EOF).

So the patch looks OK to me, although I'd still prefer a separate
fprintf() and think it would be fine for check_refcounts_l1() to call
fix_table_entry() directly.

Max


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