Patch "NFSv4: nfs4_copy_delegation_stateid() must fail if the delegation is invalid" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    NFSv4: nfs4_copy_delegation_stateid() must fail if the delegation is invalid

to the 4.4-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:
     nfsv4-nfs4_copy_delegation_stateid-must-fail-if-the-delegation-is-invalid.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From aa05c87f23efe417adc7ff9b4193b7201ec0dd79 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <trond.myklebust@primarydata.com>
Date: Thu, 22 Sep 2016 13:38:54 -0400
Subject: NFSv4: nfs4_copy_delegation_stateid() must fail if the delegation is invalid

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit aa05c87f23efe417adc7ff9b4193b7201ec0dd79 upstream.

We must not allow the use of delegations that have been revoked or are
being returned.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Fixes: 869f9dfa4d6d ("NFSv4: Fix races between nfs_remove_bad_delegation()...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfs/delegation.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -41,6 +41,17 @@ void nfs_mark_delegation_referenced(stru
 	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }
 
+static bool
+nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
+		fmode_t flags)
+{
+	if (delegation != NULL && (delegation->type & flags) == flags &&
+	    !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
+	    !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
+		return true;
+	return false;
+}
+
 static int
 nfs4_do_check_delegation(struct inode *inode, fmode_t flags, bool mark)
 {
@@ -50,9 +61,7 @@ nfs4_do_check_delegation(struct inode *i
 	flags &= FMODE_READ|FMODE_WRITE;
 	rcu_read_lock();
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
-	if (delegation != NULL && (delegation->type & flags) == flags &&
-	    !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
-	    !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags)) {
+	if (nfs4_is_valid_delegation(delegation, flags)) {
 		if (mark)
 			nfs_mark_delegation_referenced(delegation);
 		ret = 1;
@@ -893,7 +902,7 @@ bool nfs4_copy_delegation_stateid(nfs4_s
 	flags &= FMODE_READ|FMODE_WRITE;
 	rcu_read_lock();
 	delegation = rcu_dereference(nfsi->delegation);
-	ret = (delegation != NULL && (delegation->type & flags) == flags);
+	ret = nfs4_is_valid_delegation(delegation, flags);
 	if (ret) {
 		nfs4_stateid_copy(dst, &delegation->stateid);
 		nfs_mark_delegation_referenced(delegation);


Patches currently in stable-queue which might be from trond.myklebust@primarydata.com are

queue-4.4/nfsv4-don-t-report-revoked-delegations-as-valid-in-nfs_have_delegation.patch
queue-4.4/nfsv4.2-fix-a-reference-leak-in-nfs42_proc_layoutstats_generic.patch
queue-4.4/nfsv4-open-state-recovery-must-account-for-file-permission-changes.patch
queue-4.4/nfsv4-nfs4_copy_delegation_stateid-must-fail-if-the-delegation-is-invalid.patch