qcow2: Handle failure for potentially large allocations

Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.

This patch addresses the allocations in the qcow2 block driver.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/block/qcow2-cache.c b/block/qcow2-cache.c
index 8ecbb5bc00..5353b44828 100644
--- a/block/qcow2-cache.c
+++ b/block/qcow2-cache.c
@@ -53,10 +53,21 @@ Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
     c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
 
     for (i = 0; i < c->size; i++) {
-        c->entries[i].table = qemu_blockalign(bs, s->cluster_size);
+        c->entries[i].table = qemu_try_blockalign(bs->file, s->cluster_size);
+        if (c->entries[i].table == NULL) {
+            goto fail;
+        }
     }
 
     return c;
+
+fail:
+    for (i = 0; i < c->size; i++) {
+        qemu_vfree(c->entries[i].table);
+    }
+    g_free(c->entries);
+    g_free(c);
+    return NULL;
 }
 
 int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c)