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, 28 insertions, 8 deletions

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 4208dc08b5..e7c5f486cd 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -72,14 +72,20 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
 #endif
 
     new_l1_size2 = sizeof(uint64_t) * new_l1_size;
-    new_l1_table = g_malloc0(align_offset(new_l1_size2, 512));
+    new_l1_table = qemu_try_blockalign(bs->file,
+                                       align_offset(new_l1_size2, 512));
+    if (new_l1_table == NULL) {
+        return -ENOMEM;
+    }
+    memset(new_l1_table, 0, align_offset(new_l1_size2, 512));
+
     memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
 
     /* write new table (align to cluster) */
     BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
     new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
     if (new_l1_table_offset < 0) {
-        g_free(new_l1_table);
+        qemu_vfree(new_l1_table);
         return new_l1_table_offset;
     }
 
@@ -113,7 +119,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
     if (ret < 0) {
         goto fail;
     }
-    g_free(s->l1_table);
+    qemu_vfree(s->l1_table);
     old_l1_table_offset = s->l1_table_offset;
     s->l1_table_offset = new_l1_table_offset;
     s->l1_table = new_l1_table;
@@ -123,7 +129,7 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
                         QCOW2_DISCARD_OTHER);
     return 0;
  fail:
-    g_free(new_l1_table);
+    qemu_vfree(new_l1_table);
     qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
                         QCOW2_DISCARD_OTHER);
     return ret;
@@ -372,7 +378,10 @@ static int coroutine_fn copy_sectors(BlockDriverState *bs,
     }
 
     iov.iov_len = n * BDRV_SECTOR_SIZE;
-    iov.iov_base = qemu_blockalign(bs, iov.iov_len);
+    iov.iov_base = qemu_try_blockalign(bs, iov.iov_len);
+    if (iov.iov_base == NULL) {
+        return -ENOMEM;
+    }
 
     qemu_iovec_init_external(&qiov, &iov, 1);
 
@@ -702,7 +711,11 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
     trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
     assert(m->nb_clusters > 0);
 
-    old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
+    old_cluster = g_try_malloc(m->nb_clusters * sizeof(uint64_t));
+    if (old_cluster == NULL) {
+        ret = -ENOMEM;
+        goto err;
+    }
 
     /* copy content of unmodified sectors */
     ret = perform_cow(bs, m, &m->cow_start);
@@ -1562,7 +1575,10 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
     if (!is_active_l1) {
         /* inactive L2 tables require a buffer to be stored in when loading
          * them from disk */
-        l2_table = qemu_blockalign(bs, s->cluster_size);
+        l2_table = qemu_try_blockalign(bs->file, s->cluster_size);
+        if (l2_table == NULL) {
+            return -ENOMEM;
+        }
     }
 
     for (i = 0; i < l1_size; i++) {
@@ -1740,7 +1756,11 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs)
 
     nb_clusters = size_to_clusters(s, bs->file->total_sectors *
                                    BDRV_SECTOR_SIZE);
-    expanded_clusters = g_malloc0((nb_clusters + 7) / 8);
+    expanded_clusters = g_try_malloc0((nb_clusters + 7) / 8);
+    if (expanded_clusters == NULL) {
+        ret = -ENOMEM;
+        goto fail;
+    }
 
     ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
                                      &expanded_clusters, &nb_clusters);