NFSv4: Fix a use-after-free issue with the nfs server.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 97cfb143e09f..665949d27798 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -883,13 +883,15 @@ static int nfs4_get_sb(struct file_system_type *fs_type,
                 goto out_free;
         }
 
+        if (s->s_fs_info != server) {
+                nfs_free_server(server);
+                server = NULL;
+        }
+
         if (!s->s_root) {
                 /* initial superblock/root creation */
                 s->s_flags = flags;
-
                 nfs4_fill_super(s);
-        } else {
-                nfs_free_server(server);
         }
 
         mntroot = nfs4_get_root(s, &mntfh);