3 files changed, 33 insertions, 3 deletions

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index d23d5b3..4e30d16 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -33,7 +33,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, int min_size)
     BDRVQcowState *s = bs->opaque;
     int new_l1_size, new_l1_size2, ret, i;
     uint64_t *new_l1_table;
-    uint64_t new_l1_table_offset;
+    int64_t new_l1_table_offset;
     uint8_t data[12];
 
     new_l1_size = s->l1_size;
@@ -55,6 +55,10 @@ int qcow2_grow_l1_table(BlockDriverState *bs, int min_size)
 
     /* write new table (align to cluster) */
     new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
+    if (new_l1_table_offset < 0) {
+        qemu_free(new_l1_table);
+        return new_l1_table_offset;
+    }
 
     for(i = 0; i < s->l1_size; i++)
         new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
@@ -222,6 +226,9 @@ static uint64_t *l2_allocate(BlockDriverState *bs, int l1_index)
     /* allocate a new l2 entry */
 
     l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
+    if (l2_offset < 0) {
+        return NULL;
+    }
 
     /* update the L1 entry */
 
@@ -569,6 +576,10 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
         qcow2_free_any_clusters(bs, cluster_offset, 1);
 
     cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
+    if (cluster_offset < 0) {
+        return 0;
+    }
+
     nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -
                   (cluster_offset >> 9);
 
@@ -700,7 +711,8 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
 {
     BDRVQcowState *s = bs->opaque;
     int l2_index, ret;
-    uint64_t l2_offset, *l2_table, cluster_offset;
+    uint64_t l2_offset, *l2_table;
+    int64_t cluster_offset;
     unsigned int nb_clusters, i = 0;
     QCowL2Meta *old_alloc;
 
@@ -794,6 +806,9 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
     /* allocate a new cluster */
 
     cluster_offset = qcow2_alloc_clusters(bs, nb_clusters * s->cluster_size);
+    if (cluster_offset < 0) {
+        return cluster_offset;
+    }
 
     /* save info needed for meta data update */
     m->offset = offset;
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index b12299d..2fdc26b 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -435,6 +435,9 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
     assert(size > 0 && size <= s->cluster_size);
     if (s->free_byte_offset == 0) {
         s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size);
+        if (s->free_byte_offset < 0) {
+            return s->free_byte_offset;
+        }
     }
  redo:
     free_in_cluster = s->cluster_size -
@@ -450,6 +453,9 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
             update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
     } else {
         offset = qcow2_alloc_clusters(bs, s->cluster_size);
+        if (offset < 0) {
+            return offset;
+        }
         cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
         if ((cluster_offset + s->cluster_size) == offset) {
             /* we are lucky: contiguous data */
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index d63c7e1..8ddaea2 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -139,6 +139,9 @@ static int qcow_write_snapshots(BlockDriverState *bs)
 
     snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
     offset = snapshots_offset;
+    if (offset < 0) {
+        return offset;
+    }
 
     for(i = 0; i < s->nb_snapshots; i++) {
         sn = s->snapshots + i;
@@ -235,6 +238,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
     QCowSnapshot *snapshots1, sn1, *sn = &sn1;
     int i, ret;
     uint64_t *l1_table = NULL;
+    int64_t l1_table_offset;
 
     memset(sn, 0, sizeof(*sn));
 
@@ -263,7 +267,12 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
         goto fail;
 
     /* create the L1 table of the snapshot */
-    sn->l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
+    l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
+    if (l1_table_offset < 0) {
+        goto fail;
+    }
+
+    sn->l1_table_offset = l1_table_offset;
     sn->l1_size = s->l1_size;
 
     if (s->l1_size != 0) {