NFS prevent double free in async nfs4_exchange_id

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>
Cc: stable@vger.kernel.org # 4.9
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c1f5369cd3398848288c947dee682f961dc6ae59..c780d98035ccf79573c47ac8fb46b8f06a17653e 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -7425,11 +7425,11 @@ 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);
@@ -7536,10 +7536,8 @@ 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);
@@ -7567,6 +7565,7 @@ out_server_owner:
        kfree(calldata->res.server_owner);
 out_calldata:
        kfree(calldata);
+       nfs_put_client(clp);
        goto out;
 }