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qcow2: Assert against currently impossible overflow

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If qcow2_alloc_cluster_link_l2 is called with a QCowL2Meta describing a
request crossing L2 boundaries, a buffer overflow will occur. This is
impossible right now since such requests are never generated (every
request is shortened to L2 boundaries before) and probably also
completely unintended (considering the name "QCowL2Meta"), however, it
is still worth an assertion.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2013-09-25 17:48:55 +02:00 committed by Kevin Wolf
parent 687fb89366
commit c01dbccbad
1 changed files with 1 additions and 0 deletions
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block/qcow2-cluster.c
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@ -716,6 +716,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
}
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
assert(l2_index + m->nb_clusters <= s->l2_size);
for (i = 0; i < m->nb_clusters; i++) {
/* if two concurrent writes happen to the same unallocated cluster
* each write allocates separate cluster and writes data concurrently.