Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain; charset="UTF-8"
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
MIME-Version: 1.0
From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "J. Bruce Fields" <bfields@redhat.com>,
        "Jeff Layton" <jlayton@primarydata.com>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.655951405@decadent.org.uk>
Subject: [PATCH 3.16 201/366] nfsd: silence sparse warning about accessing
 credentials
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jeff Layton <jlayton@primarydata.com>

commit ae4b884fc6316b3190be19448cea24b020c1cad6 upstream.

sparse says:

    fs/nfsd/auth.c:31:38: warning: incorrect type in argument 1 (different address spaces)
    fs/nfsd/auth.c:31:38:    expected struct cred const *cred
    fs/nfsd/auth.c:31:38:    got struct cred const [noderef] <asn:4>*real_cred

Add a new accessor for the ->real_cred and use that to fetch the
pointer. Accessing current->real_cred directly is actually quite safe
since we know that they can't go away so this is mostly a cosmetic fixup
to silence sparse.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/nfsd/auth.c       | 2 +-
 include/linux/cred.h | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

--- a/fs/nfsd/auth.c
+++ b/fs/nfsd/auth.c
@@ -28,7 +28,7 @@ int nfsd_setuser(struct svc_rqst *rqstp,
 	validate_process_creds();
 
 	/* discard any old override before preparing the new set */
-	revert_creds(get_cred(current->real_cred));
+	revert_creds(get_cred(current_real_cred()));
 	new = prepare_creds();
 	if (!new)
 		return -ENOMEM;
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -261,6 +261,15 @@ static inline void put_cred(const struct
 	rcu_dereference_protected(current->cred, 1)
 
 /**
+ * current_real_cred - Access the current task's objective credentials
+ *
+ * Access the objective credentials of the current task.  RCU-safe,
+ * since nobody else can modify it.
+ */
+#define current_real_cred() \
+	rcu_dereference_protected(current->real_cred, 1)
+
+/**
  * __task_cred - Access a task's objective credentials
  * @task: The task to query
  *