SUNRPC: Fix validity issues with rpc_pipefs sb->s_fs_info

[firefly-linux-kernel-4.4.55.git] / net / sunrpc / rpc_pipe.c

diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 80f5dd23417d92c932be96225b8c65723774aa40..e659def7774295794511679c75440ae971216bbf 100644 (file)
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1152,14 +1152,19 @@ static void rpc_kill_sb(struct super_block *sb)
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
 
        mutex_lock(&sn->pipefs_sb_lock);
+       if (sn->pipefs_sb != sb) {
+               mutex_unlock(&sn->pipefs_sb_lock);
+               goto out;
+       }
        sn->pipefs_sb = NULL;
        mutex_unlock(&sn->pipefs_sb_lock);
-       put_net(net);
        dprintk("RPC:       sending pipefs UMOUNT notification for net %p%s\n",
                net, NET_NAME(net));
        blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
                                           RPC_PIPEFS_UMOUNT,
                                           sb);
+       put_net(net);
+out:
        kill_litter_super(sb);
 }