NFS: Fix infinite loop in gss_create_upcall()

There can be an infinite loop if gss_create_upcall() is called without
the userspace program running.  To prevent this, we return -EACCES if
we notice that pipe_version hasn't changed (indicating that the pipe
has not been opened).

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>

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

1 files changed, 5 insertions, 3 deletions

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index f3914d0c507..339ba64cce1 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -520,7 +520,7 @@ gss_refresh_upcall(struct rpc_task *task)
                 warn_gssd();
                 task->tk_timeout = 15*HZ;
                 rpc_sleep_on(&pipe_version_rpc_waitqueue, task, NULL);
-                return 0;
+                return -EAGAIN;
         }
         if (IS_ERR(gss_msg)) {
                 err = PTR_ERR(gss_msg);
@@ -563,10 +563,12 @@ retry:
         if (PTR_ERR(gss_msg) == -EAGAIN) {
                 err = wait_event_interruptible_timeout(pipe_version_waitqueue,
                                 pipe_version >= 0, 15*HZ);
+                if (pipe_version < 0) {
+                        warn_gssd();
+                        err = -EACCES;
+                }
                 if (err)
                         goto out;
-                if (pipe_version < 0)
-                        warn_gssd();
                 goto retry;
         }
         if (IS_ERR(gss_msg)) {