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authorMax Reitz <mreitz@redhat.com>2014-05-04 05:31:40 +0200
committerStefan Hajnoczi <stefanha@redhat.com>2014-05-09 13:32:16 +0200
commit65f33bc0020112e7be7b8966495cd5efa2d0ab15 (patch)
tree45cd51192d53cf9f20140c3e9bd253f47ab344e3 /block/qcow2-refcount.c
parent43cbeffb19877c62cbe0aaf08b2f235d98d71340 (diff)
qcow2: Fix alloc_clusters_noref() overflow detection
If the very first allocation has a length of 0, the free_cluster_index is still 0 after the for loop, which means that subtracting one from it will underflow and signal an invalid range of clusters by returning -EFBIG. However, there is no such range, as its length is 0. Fix this by preventing underflows on free_cluster_index during the check. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r--block/qcow2-refcount.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index e79895d11d..9507aef847 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -656,7 +656,9 @@ retry:
/* Make sure that all offsets in the "allocated" range are representable
* in an int64_t */
- if (s->free_cluster_index - 1 > (INT64_MAX >> s->cluster_bits)) {
+ if (s->free_cluster_index > 0 &&
+ s->free_cluster_index - 1 > (INT64_MAX >> s->cluster_bits))
+ {
return -EFBIG;
}