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ipc: convert ipc_namespace.count from atomic_t to refcount_t

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refcount_t type and corresponding API should be used instead of atomic_t
when the variable is used as a reference counter.  This allows to avoid
accidental refcounter overflows that might lead to use-after-free
situations.

Link: http://lkml.kernel.org/r/1499417992-3238-2-git-send-email-elena.reshetova@intel.com
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: <arozansk@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Elena Reshetova 2017-09-08 16:17:38 -07:00 committed by Linus Torvalds
parent 7483e5d420
commit a2e0602c36
3 changed files with 6 additions and 5 deletions
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5
include/linux/ipc_namespace.h
View file

@ -7,6 +7,7 @@
#include <linux/notifier.h>
#include <linux/nsproxy.h>
#include <linux/ns_common.h>
#include <linux/refcount.h>
struct user_namespace;
@ -19,7 +20,7 @@ struct ipc_ids {
};
struct ipc_namespace {
atomic_t count;
refcount_t count;
struct ipc_ids ids[3];
int sem_ctls[4];
@ -118,7 +119,7 @@ extern struct ipc_namespace *copy_ipcs(unsigned long flags,
static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
{
if (ns)
atomic_inc(&ns->count);
refcount_inc(&ns->count);
return ns;
}

2
ipc/msgutil.c
View file

@ -29,7 +29,7 @@ DEFINE_SPINLOCK(mq_lock);
* and not CONFIG_IPC_NS.
*/
struct ipc_namespace init_ipc_ns = {
.count = ATOMIC_INIT(1),
.count = REFCOUNT_INIT(1),
.user_ns = &init_user_ns,
.ns.inum = PROC_IPC_INIT_INO,
#ifdef CONFIG_IPC_NS

4
ipc/namespace.c
View file

@ -50,7 +50,7 @@ static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
goto fail_free;
ns->ns.ops = &ipcns_operations;
atomic_set(&ns->count, 1);
refcount_set(&ns->count, 1);
ns->user_ns = get_user_ns(user_ns);
ns->ucounts = ucounts;
@ -144,7 +144,7 @@ static void free_ipc_ns(struct ipc_namespace *ns)
*/
void put_ipc_ns(struct ipc_namespace *ns)
{
if (atomic_dec_and_lock(&ns->count, &mq_lock)) {
if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
mq_clear_sbinfo(ns);
spin_unlock(&mq_lock);
mq_put_mnt(ns);