path: root/drivers/net/ppp
diff options
authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 10:23:46 +0300
committerDavid S. Miller <davem@davemloft.net>2017-10-22 02:22:39 +0100
commit313a912155c78ed87ad6fca175dc56b75fd00a58 (patch)
tree265fd14a918c1eddf6799edd2f7981bbb5658d2f /drivers/net/ppp
parentdrivers, net: convert masces_tx_sa.refcnt from atomic_t to refcount_t (diff)
drivers, net, ppp: convert asyncppp.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 asyncppp.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>
Diffstat (limited to 'drivers/net/ppp')
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/net/ppp/ppp_async.c b/drivers/net/ppp/ppp_async.c
index 814fd8fae67d..1b28e6e702f5 100644
--- a/drivers/net/ppp/ppp_async.c
+++ b/drivers/net/ppp/ppp_async.c
@@ -69,7 +69,7 @@ struct asyncppp {
struct tasklet_struct tsk;
- atomic_t refcnt;
+ refcount_t refcnt;
struct semaphore dead_sem;
struct ppp_channel chan; /* interface to generic ppp layer */
unsigned char obuf[OBUFSIZE];
@@ -140,14 +140,14 @@ static struct asyncppp *ap_get(struct tty_struct *tty)
ap = tty->disc_data;
if (ap != NULL)
- atomic_inc(&ap->refcnt);
+ refcount_inc(&ap->refcnt);
return ap;
static void ap_put(struct asyncppp *ap)
- if (atomic_dec_and_test(&ap->refcnt))
+ if (refcount_dec_and_test(&ap->refcnt))
@@ -185,7 +185,7 @@ ppp_asynctty_open(struct tty_struct *tty)
tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
- atomic_set(&ap->refcnt, 1);
+ refcount_set(&ap->refcnt, 1);
sema_init(&ap->dead_sem, 0);
ap->chan.private = ap;
@@ -234,7 +234,7 @@ ppp_asynctty_close(struct tty_struct *tty)
* our channel ops (i.e. ppp_async_send/ioctl) are in progress
* by the time it returns.
- if (!atomic_dec_and_test(&ap->refcnt))
+ if (!refcount_dec_and_test(&ap->refcnt))