[PATCH 3.16 151/366] rpc_pipefs: fix double-dput()

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

commit 4a3877c4cedd95543f8726b0a98743ed8db0c0fb upstream.

if we ever hit rpc_gssd_dummy_depopulate() dentry passed to
it has refcount equal to 1.  __rpc_rmpipe() drops it and
dput() done after that hits an already freed dentry.

Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/sunrpc/rpc_pipe.c | 1 +
 1 file changed, 1 insertion(+)

--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1375,6 +1375,7 @@ rpc_gssd_dummy_depopulate(struct dentry
 	struct dentry *clnt_dir = pipe_dentry->d_parent;
 	struct dentry *gssd_dir = clnt_dir->d_parent;
 
+	dget(pipe_dentry);
 	__rpc_rmpipe(clnt_dir->d_inode, pipe_dentry);
 	__rpc_depopulate(clnt_dir, gssd_dummy_info_file, 0, 1);
 	__rpc_depopulate(gssd_dir, gssd_dummy_clnt_dir, 0, 1);