17.08.2018 15:22, Vladimir Sementsov-Ogievskiy wrote:
> Rewrite corrupted L2 table entry, which reference space out of
> underlying file.
>
> Make this L2 table entry read-as-all-zeros without any allocation.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
> ---
> block/qcow2-refcount.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 3c004e5bfe..3de3768a3c 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -1720,8 +1720,30 @@ static int check_refcounts_l2(BlockDriverState *bs,
> BdrvCheckResult *res,
> /* Mark cluster as used */
> csize = (((l2_entry >> s->csize_shift) & s->csize_mask) + 1) *
> BDRV_SECTOR_SIZE;
> + if (csize > s->cluster_size) {
> + ret = fix_l2_entry_to_zero(
> + bs, res, fix, l2_offset, i, active,
> + "compressed cluster larger than cluster: size 0x%"
> + PRIx64, csize);
> + if (ret < 0) {
> + goto fail;
> + }
> + continue;
> + }
> +
> coffset = l2_entry & s->cluster_offset_mask &
> ~(BDRV_SECTOR_SIZE - 1);
> + if (coffset >= bdrv_getlength(bs->file->bs)) {
> + ret = fix_l2_entry_to_zero(
> + bs, res, fix, l2_offset, i, active,
> + "compressed cluster out of file: offset 0x%" PRIx64,
> + coffset);
> + if (ret < 0) {
> + goto fail;
> + }
> + continue;
> + }
> +
> ret = qcow2_inc_refcounts_imrt(bs, res,
> refcount_table,
> refcount_table_size,
> coffset, csize);
> @@ -1748,6 +1770,16 @@ static int check_refcounts_l2(BlockDriverState *bs,
> BdrvCheckResult *res,
> {
> uint64_t offset = l2_entry & L2E_OFFSET_MASK;
>
> + if (offset >= bdrv_getlength(bs->file->bs)) {
> + ret = fix_l2_entry_to_zero(
> + bs, res, fix, l2_offset, i, active,
> + "cluster out of file: offset 0x%" PRIx64, offset);
> + if (ret < 0) {
> + goto fail;
> + }
> + continue;
> + }
> +
> if (flags & CHECK_FRAG_INFO) {
> res->bfi.allocated_clusters++;
> if (next_contiguous_offset &&
hmm, interesting question here: in case of misaligned l2 entry, we zero
it out only for QCOW2_CLUSTER_ZERO_ALLOC, but not for normal clusters?
Why? I think it is ok to mark as zero misaligned normal cluster l2
entry, otherwise we'll have fatal corruption on any operation to this
cluster.
--
Best regards,
Vladimir
