diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-12-20 20:10:55 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-12-20 15:23:44 -0500 |
| commit | c380cd5a00f32a96b6c63148a939eb9f8836e184 (patch) | |
| tree | e4cfa93ba6e47340d122c234027fa934776ac43a /drivers | |
| parent | a943e8bc058977663ba1e42389d4f5643cf2ae9e (diff) | |
net: convert lcs_reply.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 lcs_reply.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>
[jwi: removed the WARN_ONs. Use CONFIG_REFCOUNT_FULL if you care.]
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/s390/net/lcs.c | 10 | ||||
| -rw-r--r-- | drivers/s390/net/lcs.h | 3 |
2 files changed, 5 insertions, 8 deletions
diff --git a/drivers/s390/net/lcs.c b/drivers/s390/net/lcs.c index 92ae84a927fc..0ee8f33efb54 100644 --- a/drivers/s390/net/lcs.c +++ b/drivers/s390/net/lcs.c @@ -756,18 +756,14 @@ lcs_get_lancmd(struct lcs_card *card, int count) static void lcs_get_reply(struct lcs_reply *reply) { - WARN_ON(atomic_read(&reply->refcnt) <= 0); - atomic_inc(&reply->refcnt); + refcount_inc(&reply->refcnt); } static void lcs_put_reply(struct lcs_reply *reply) { - WARN_ON(atomic_read(&reply->refcnt) <= 0); - if (atomic_dec_and_test(&reply->refcnt)) { + if (refcount_dec_and_test(&reply->refcnt)) kfree(reply); - } - } static struct lcs_reply * @@ -780,7 +776,7 @@ lcs_alloc_reply(struct lcs_cmd *cmd) reply = kzalloc(sizeof(struct lcs_reply), GFP_ATOMIC); if (!reply) return NULL; - atomic_set(&reply->refcnt,1); + refcount_set(&reply->refcnt, 1); reply->sequence_no = cmd->sequence_no; reply->received = 0; reply->rc = 0; diff --git a/drivers/s390/net/lcs.h b/drivers/s390/net/lcs.h index fbc8b90b1f85..bd52caa3b11b 100644 --- a/drivers/s390/net/lcs.h +++ b/drivers/s390/net/lcs.h @@ -5,6 +5,7 @@ #include <linux/netdevice.h> #include <linux/skbuff.h> #include <linux/workqueue.h> +#include <linux/refcount.h> #include <asm/ccwdev.h> #define LCS_DBF_TEXT(level, name, text) \ @@ -271,7 +272,7 @@ struct lcs_buffer { struct lcs_reply { struct list_head list; __u16 sequence_no; - atomic_t refcnt; + refcount_t refcnt; /* Callback for completion notification. */ void (*callback)(struct lcs_card *, struct lcs_cmd *); wait_queue_head_t wait_q; |