NFS prevent double free in async nfs4_exchange_id

commit 63513232f8cd219dcaa5eafae028740ed3067d83 upstream.

Since rpc_task is async, the release function should be called which
will free the impl_id, scope, and owner.

Trond pointed at 2 more problems:
-- use of client pointer after free in the nfs4_exchangeid_release() function
-- cl_count mismatch if rpc_run_task() isn't run

Fixes: 8d89bd70bc9 ("NFS setup async exchange_id")
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 609840de31d3..1536aeb0abab 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7426,11 +7426,11 @@ static void nfs4_exchange_id_release(void *data)
         struct nfs41_exchange_id_data *cdata =
                                         (struct nfs41_exchange_id_data *)data;
 
-        nfs_put_client(cdata->args.client);
         if (cdata->xprt) {
                 xprt_put(cdata->xprt);
                 rpc_clnt_xprt_switch_put(cdata->args.client->cl_rpcclient);
         }
+        nfs_put_client(cdata->args.client);
         kfree(cdata->res.impl_id);
         kfree(cdata->res.server_scope);
         kfree(cdata->res.server_owner);
@@ -7537,10 +7537,8 @@ static int _nfs4_proc_exchange_id(struct nfs_client *clp, struct rpc_cred *cred,
         task_setup_data.callback_data = calldata;
 
         task = rpc_run_task(&task_setup_data);
-        if (IS_ERR(task)) {
-        status = PTR_ERR(task);
-                goto out_impl_id;
-        }
+        if (IS_ERR(task))
+                return PTR_ERR(task);
 
         if (!xprt) {
                 status = rpc_wait_for_completion_task(task);
@@ -7568,6 +7566,7 @@ out_server_owner:
         kfree(calldata->res.server_owner);
 out_calldata:
         kfree(calldata);
+        nfs_put_client(clp);
         goto out;
 }