Patch "NFS prevent double free in async nfs4_exchange_id" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

NFS prevent double free in async nfs4_exchange_id

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfs-prevent-double-free-in-async-nfs4_exchange_id.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Olga Kornievskaia <[email protected]>
Date: Mon, 13 Mar 2017 10:36:19 -0400
Subject: NFS prevent double free in async nfs4_exchange_id

From: Olga Kornievskaia <[email protected]>

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

---
 fs/nfs/nfs4proc.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

@@ -7426,11 +7426,11 @@ static void nfs4_exchange_id_release(voi
 	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
 	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;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/nfs-prevent-double-free-in-async-nfs4_exchange_id.patch