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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, stable@kernel.org,
        Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH 4.9 89/95] rpc_pipefs: fix double-dput()
Date:   Sun, 22 Apr 2018 15:53:58 +0200
Message-Id: <20180422135214.068435004@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

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

From: Al Viro <viro@zeniv.linux.org.uk>

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.

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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(d_inode(clnt_dir), pipe_dentry);
 	__rpc_depopulate(clnt_dir, gssd_dummy_info_file, 0, 1);
 	__rpc_depopulate(gssd_dir, gssd_dummy_clnt_dir, 0, 1);