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Subject[PATCH 08/16] drivers, net, hamradio: convert sixpack.refcnt from atomic_t to refcount_t
Date
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 <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>
---
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 922bf44..ea6c975 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);
}

@@ -580,7 +580,7 @@ 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! */
@@ -676,7 +676,7 @@ 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
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