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.
Signed-off-by: Elena Reshetova <[email protected]> Signed-off-by: Hans Liljestrand <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: David Windsor <[email protected]> --- include/linux/ipc_namespace.h | 5 +++-- ipc/msgutil.c | 2 +- ipc/namespace.c | 4 ++-- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h index 848e579..7230638 100644 --- a/include/linux/ipc_namespace.h +++ b/include/linux/ipc_namespace.h @@ -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; } diff --git a/ipc/msgutil.c b/ipc/msgutil.c index bf74eaa..8459802 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -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 diff --git a/ipc/namespace.c b/ipc/namespace.c index 0abdea4..ed10bbc 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -48,7 +48,7 @@ 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; @@ -142,7 +142,7 @@ 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); -- 2.7.4
