qcow2: fix offset overflow in qcow2_alloc_clusters_at()
When cluster size is big enough it can lead to an offset overflow in qcow2_alloc_clusters_at(). This patch fixes it. The allocation is stopped each time at L2 table boundary (see handle_alloc()), so the possible maximum bytes could be 2^(cluster_bits - 3 + cluster_bits) cluster_bits - 3 is used to compute the number of entry by L2 and the additional cluster_bits is to take into account each clusters referenced by the L2 entries. so int is safe for cluster_bits<=17, unsafe otherwise. Signed-off-by: NHu Tao <hutao@cn.fujitsu.com> Reviewed-by: NMax Reitz <mreitz@redhat.com> Reviewed-by: NBenoit Canet <benoit@irqsave.net> Signed-off-by: NKevin Wolf <kwolf@redhat.com>
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