From: Max Reitz Date: Wed, 25 Sep 2013 15:48:55 +0000 (+0200) Subject: qcow2: Assert against currently impossible overflow X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c01dbccbad647be5784be39eb8fa0144732295db;p=qemu.git qcow2: Assert against currently impossible overflow 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 Signed-off-by: Kevin Wolf --- diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 738ff73c1d..cab5f2e6b5 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -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.