From 91f827dcff61c3e007def4c949d3a8310954b85e Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Tue, 29 Apr 2014 19:03:11 +0200 Subject: qcow2: Avoid overflow in alloc_clusters_noref() alloc_clusters_noref() stores the cluster index in a uint64_t. However, offsets are often represented as int64_t (as for example the return value of alloc_clusters_noref() itself demonstrates). Therefore, we should make sure all offsets in the allocated range of clusters are representable using int64_t without overflows. Signed-off-by: Max Reitz Signed-off-by: Kevin Wolf --- block/qcow2-refcount.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'block') diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index a37ee45016..d2cb6a8775 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -653,6 +653,13 @@ retry: goto 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)) { + return -EFBIG; + } + #ifdef DEBUG_ALLOC2 fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", size, -- cgit v1.2.1