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-rw-r--r--block/qcow2-refcount.c4
-rw-r--r--block/qcow2.c9
2 files changed, 12 insertions, 1 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 4a2df5fb99..e3c7ecdcc9 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -40,8 +40,10 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int qcow2_refcount_init(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
- int ret, refcount_table_size2, i;
+ unsigned int refcount_table_size2, i;
+ int ret;
+ assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t));
refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
s->refcount_table = g_malloc(refcount_table_size2);
if (s->refcount_table_size > 0) {
diff --git a/block/qcow2.c b/block/qcow2.c
index f0411a9217..b9b6e70264 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -577,10 +577,19 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
s->csize_shift = (62 - (s->cluster_bits - 8));
s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
+
s->refcount_table_offset = header.refcount_table_offset;
s->refcount_table_size =
header.refcount_table_clusters << (s->cluster_bits - 3);
+ if (header.refcount_table_clusters > (0x800000 >> s->cluster_bits)) {
+ /* 8 MB refcount table is enough for 2 PB images at 64k cluster size
+ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
+ error_setg(errp, "Reference count table too large");
+ ret = -EINVAL;
+ goto fail;
+ }
+
s->snapshots_offset = header.snapshots_offset;
s->nb_snapshots = header.nb_snapshots;