SUNRPC: Fix a race in gss_refresh_upcall()

If the downcall completes before we get the spin_lock then we currently
fail to refresh the credential.

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

1 files changed, 8 insertions, 3 deletions

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 46f7ec800af9..6f1b4e2f5e81 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -117,6 +117,7 @@ gss_cred_set_ctx(struct rpc_cred *cred, struct gss_cl_ctx *ctx)
         struct gss_cl_ctx *old;
 
         old = gss_cred->gc_ctx;
+        gss_get_ctx(ctx);
         rcu_assign_pointer(gss_cred->gc_ctx, ctx);
         set_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
         clear_bit(RPCAUTH_CRED_NEW, &cred->cr_flags);
@@ -340,7 +341,7 @@ gss_upcall_callback(struct rpc_task *task)
 
         spin_lock(&inode->i_lock);
         if (gss_msg->ctx)
-                gss_cred_set_ctx(task->tk_msg.rpc_cred, gss_get_ctx(gss_msg->ctx));
+                gss_cred_set_ctx(task->tk_msg.rpc_cred, gss_msg->ctx);
         else
                 task->tk_status = gss_msg->msg.errno;
         gss_cred->gc_upcall = NULL;
@@ -417,7 +418,11 @@ gss_refresh_upcall(struct rpc_task *task)
         spin_lock(&inode->i_lock);
         if (gss_cred->gc_upcall != NULL)
                 rpc_sleep_on(&gss_cred->gc_upcall->rpc_waitqueue, task, NULL);
-        else if (gss_msg->ctx == NULL && gss_msg->msg.errno >= 0) {
+        else if (gss_msg->ctx != NULL) {
+                gss_cred_set_ctx(task->tk_msg.rpc_cred, gss_msg->ctx);
+                gss_cred->gc_upcall = NULL;
+                rpc_wake_up_status(&gss_msg->rpc_waitqueue, gss_msg->msg.errno);
+        } else if (gss_msg->msg.errno >= 0) {
                 task->tk_timeout = 0;
                 gss_cred->gc_upcall = gss_msg;
                 /* gss_upcall_callback will release the reference to gss_upcall_msg */
@@ -462,7 +467,7 @@ gss_create_upcall(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
                 schedule();
         }
         if (gss_msg->ctx)
-                gss_cred_set_ctx(cred, gss_get_ctx(gss_msg->ctx));
+                gss_cred_set_ctx(cred, gss_msg->ctx);
         else
                 err = gss_msg->msg.errno;
         spin_unlock(&inode->i_lock);