[PATCH 08/15] drivers, net, hamradio: convert sixpack.refcnt from atomic_t to refcount_t
From: elena.reshetova@intel.com (Elena Reshetova)
Date: 2017-10-20 07:25:18
Also in:
linux-hams, linux-mediatek, linux-rdma, lkml, netdev
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable sixpack.refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <redacted> Reviewed-by: David Windsor <redacted> Reviewed-by: Hans Liljestrand <redacted> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- drivers/net/hamradio/6pack.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index bbc7b78..32f49c4 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c@@ -35,7 +35,7 @@ #include <linux/tcp.h> #include <linux/semaphore.h> #include <linux/compat.h> -#include <linux/atomic.h> +#include <linux/refcount.h> #define SIXPACK_VERSION "Revision: 0.3.0"
@@ -120,7 +120,7 @@ struct sixpack { struct timer_list tx_t; struct timer_list resync_t; - atomic_t refcnt; + refcount_t refcnt; struct semaphore dead_sem; spinlock_t lock; };
@@ -381,7 +381,7 @@ static struct sixpack *sp_get(struct tty_struct *tty) read_lock(&disc_data_lock); sp = tty->disc_data; if (sp) - atomic_inc(&sp->refcnt); + refcount_inc(&sp->refcnt); read_unlock(&disc_data_lock); return sp;
@@ -389,7 +389,7 @@ static struct sixpack *sp_get(struct tty_struct *tty) static void sp_put(struct sixpack *sp) { - if (atomic_dec_and_test(&sp->refcnt)) + if (refcount_dec_and_test(&sp->refcnt)) up(&sp->dead_sem); }
@@ -576,7 +576,7 @@ static int sixpack_open(struct tty_struct *tty) sp->dev = dev; spin_lock_init(&sp->lock); - atomic_set(&sp->refcnt, 1); + refcount_set(&sp->refcnt, 1); sema_init(&sp->dead_sem, 0); /* !!! length of the buffers. MTU is IP MTU, not PACLEN! */
@@ -670,7 +670,7 @@ static void sixpack_close(struct tty_struct *tty) * We have now ensured that nobody can start using ap from now on, but * we have to wait for all existing users to finish. */ - if (!atomic_dec_and_test(&sp->refcnt)) + if (!refcount_dec_and_test(&sp->refcnt)) down(&sp->dead_sem); /* We must stop the queue to avoid potentially scribbling
--
2.7.4