[PATCH 3.16 201/366] nfsd: silence sparse warning about accessing credentials

Ben Hutchings
2018-11-12T05:48:35Z

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
*