qcow2: Fix leak of QemuOpts in qcow2_open()

Currently, the QemuOpts object opts is leaked if anything fails from its
creation up to and including the image repair block. Fix this by freeing
that object in the fail path.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoît Canet <benoit.canet@nodalink.com>
Message-id: 1408557576-14574-2-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

block/qcow2.c

@@ -538,7 +538,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     unsigned int len, i;
     int ret = 0;
     QCowHeader header;
-    QemuOpts *opts;
+    QemuOpts *opts = NULL;
     Error *local_err = NULL;
     uint64_t ext_end;
     uint64_t l1_vm_state_index;
@@ -935,7 +935,6 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
         error_setg(errp, "Unsupported value '%s' for qcow2 option "
                    "'overlap-check'. Allowed are either of the following: "
                    "none, constant, cached, all", opt_overlap_check);
-        qemu_opts_del(opts);
         ret = -EINVAL;
         goto fail;
     }
@@ -950,6 +949,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     qemu_opts_del(opts);
+    opts = NULL;
 
     if (s->use_lazy_refcounts && s->qcow_version < 3) {
         error_setg(errp, "Lazy refcounts require a qcow2 image with at least "
@@ -967,6 +967,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     return ret;
 
  fail:
+    qemu_opts_del(opts);
     g_free(s->unknown_header_fields);
     cleanup_unknown_header_ext(bs);
     qcow2_free_snapshots(bs);