[PATCH 3.10 32/79] nfs4: fix discover_server_trunking use after free

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

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

From: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>

commit abad2fa5ba67725a3f9c376c8cfe76fbe94a3041 upstream.

If clp is new (cl_count = 1) and it matches another client in
nfs4_discover_server_trunking, the nfs_put_client will free clp before
->cl_preserve_clid is set.

Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/nfs/nfs4client.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -240,13 +240,11 @@ struct nfs_client *nfs4_init_client(stru
 	error = nfs4_discover_server_trunking(clp, &old);
 	if (error < 0)
 		goto error;
-	nfs_put_client(clp);
-	if (clp != old) {
-		clp->cl_preserve_clid = true;
-		clp = old;
-	}
 
-	return clp;
+	if (clp != old)
+		clp->cl_preserve_clid = true;
+	nfs_put_client(clp);
+	return old;
 
 error:
 	nfs_mark_client_ready(clp, error);


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