qcow2: Don't put invalid L2 table into cache

In l2_allocate, the fail path is executed if qcow2_cache_flush fails.
However, the L2 table has not yet been fetched from the L2 table cache.
The qcow2_cache_put in the fail path therefore basically gives an
undefined argument as the L2 table address (in this case).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index ffa89411d8..153ea508bc 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -188,7 +188,7 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
 {
     BDRVQcowState *s = bs->opaque;
     uint64_t old_l2_offset;
-    uint64_t *l2_table;
+    uint64_t *l2_table = NULL;
     int64_t l2_offset;
     int ret;
 
@@ -265,7 +265,9 @@ static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
 
 fail:
     trace_qcow2_l2_allocate_done(bs, l1_index, ret);
-    qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
+    if (l2_table != NULL) {
+        qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
+    }
     s->l1_table[l1_index] = old_l2_offset;
     return ret;
 }