When cluster size is big enough it can lead offset overflow
in qcow2_alloc_clusters_at(). This patch fixes it.
The allocation each time is stopped at L2 table boundary
(see handle_alloc()), so the possible maximum bytes could be
2^(cluster_bits - 3 + cluster_bits)
so int is safe for cluster_bits<=17, unsafe otherwise.
Signed-off-by: Hu Tao <hu...@cn.fujitsu.com>
---
block/qcow2-refcount.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index c974abe..8712d8b 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -676,7 +676,13 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t
offset,
BDRVQcowState *s = bs->opaque;
uint64_t cluster_index;
uint64_t old_free_cluster_index;
- int i, refcount, ret;
+ uint64_t i;
+ int refcount, ret;
+
+ assert(nb_clusters >= 0);
+ if (nb_clusters == 0) {
+ return 0;
+ }
/* Check how many clusters there are free */
cluster_index = offset >> s->cluster_bits;
--
1.8.5.2.229.g4448466
