diff options
| author | Max Reitz <mreitz@redhat.com> | 2014-05-04 05:31:40 +0200 |
|---|---|---|
| committer | Stefan Hajnoczi <stefanha@redhat.com> | 2014-05-09 13:32:16 +0200 |
| commit | 65f33bc0020112e7be7b8966495cd5efa2d0ab15 (patch) | |
| tree | 45cd51192d53cf9f20140c3e9bd253f47ab344e3 | |
| parent | 43cbeffb19877c62cbe0aaf08b2f235d98d71340 (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>
| -rw-r--r-- | block/qcow2-refcount.c | 4 |
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; } |