This is a note to let you know that I've just added the patch titled
cred: allow get_cred() and put_cred() to be given NULL.
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:
cred-allow-get_cred-and-put_cred-to-be-given-null.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@xxxxxxxxxxxxxxx> know about it.
>From f06bc03339ad4c1baa964a5f0606247ac1c3c50b Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxxx>
Date: Mon, 3 Dec 2018 11:30:30 +1100
Subject: cred: allow get_cred() and put_cred() to be given NULL.
From: NeilBrown <neilb@xxxxxxxx>
commit f06bc03339ad4c1baa964a5f0606247ac1c3c50b upstream.
It is common practice for helpers like this to silently,
accept a NULL pointer.
get_rpccred() and put_rpccred() used by NFS act this way
and using the same interface will ease the conversion
for NFS, and simplify the resulting code.
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/cred.h | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -243,7 +243,7 @@ static inline struct cred *get_new_cred(
* @cred: The credentials to reference
*
* Get a reference on the specified set of credentials. The caller must
- * release the reference.
+ * release the reference. If %NULL is passed, it is returned with no action.
*
* This is used to deal with a committed set of credentials. Although the
* pointer is const, this will temporarily discard the const and increment the
@@ -254,6 +254,8 @@ static inline struct cred *get_new_cred(
static inline const struct cred *get_cred(const struct cred *cred)
{
struct cred *nonconst_cred = (struct cred *) cred;
+ if (!cred)
+ return cred;
validate_creds(cred);
nonconst_cred->non_rcu = 0;
return get_new_cred(nonconst_cred);
@@ -264,7 +266,7 @@ static inline const struct cred *get_cre
* @cred: The credentials to release
*
* Release a reference to a set of credentials, deleting them when the last ref
- * is released.
+ * is released. If %NULL is passed, nothing is done.
*
* This takes a const pointer to a set of credentials because the credentials
* on task_struct are attached by const pointers to prevent accidental
@@ -274,9 +276,11 @@ static inline void put_cred(const struct
{
struct cred *cred = (struct cred *) _cred;
- validate_creds(cred);
- if (atomic_dec_and_test(&(cred)->usage))
- __put_cred(cred);
+ if (cred) {
+ validate_creds(cred);
+ if (atomic_dec_and_test(&(cred)->usage))
+ __put_cred(cred);
+ }
}
/**
Patches currently in stable-queue which might be from neilb@xxxxxxxx are
queue-4.4/cred-allow-get_cred-and-put_cred-to-be-given-null.patch
