rbd: Fix use after free in rbd_open()

Commit a9ccedc3 frees the QemuOpts for the driver-specific options
immediately, even though it still needs the filename string that is
contained there. This doesn't work. Move the deletion of the QemuOpts to
the end of the function where its content isn't needed any more.

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

1 files changed, 6 insertions, 3 deletions

diff --git a/block/rbd.c b/block/rbd.c
index 1826411492..0f2608b287 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -478,20 +478,20 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags)
     }
 
     filename = qemu_opt_get(opts, "filename");
-    qemu_opts_del(opts);
 
     if (qemu_rbd_parsename(filename, pool, sizeof(pool),
                            snap_buf, sizeof(snap_buf),
                            s->name, sizeof(s->name),
                            conf, sizeof(conf)) < 0) {
-        return -EINVAL;
+        r = -EINVAL;
+        goto failed_opts;
     }
 
     clientname = qemu_rbd_parse_clientname(conf, clientname_buf);
     r = rados_create(&s->cluster, clientname);
     if (r < 0) {
         error_report("error initializing");
-        return r;
+        goto failed_opts;
     }
 
     s->snap = NULL;
@@ -557,6 +557,7 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags)
                             NULL, qemu_rbd_aio_flush_cb, s);
 
 
+    qemu_opts_del(opts);
     return 0;
 
 failed:
@@ -566,6 +567,8 @@ failed_open:
 failed_shutdown:
     rados_shutdown(s->cluster);
     g_free(s->snap);
+failed_opts:
+    qemu_opts_del(opts);
     return r;
 }