diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-10-20 10:23:42 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-10-22 04:22:39 +0300 |
| commit | 956cc1e70c55ba4d5f87b9605ee727bbd225d56d (patch) | |
| tree | c203576e4688dafd00bbfcb1ddbc99189bf81e4b | |
| parent | dd8e19456d60a519de1852ae4b1be7d62690d2e0 (diff) | |
| download | linux-956cc1e70c55ba4d5f87b9605ee727bbd225d56d.tar.xz | |
drivers, net, hamradio: convert sixpack.refcnt from atomic_t to refcount_t
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 <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | drivers/net/hamradio/6pack.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index bbc7b7808a31..32f49c4ce457 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 |