[PATCH 02/29] drivers, firewire: convert fw_node.ref_count from atomic_t to refcount_t

Elena Reshetova
2017-03-06T14:20:49Z

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/firewire/core-topology.c | 2 +-
drivers/firewire/core.h | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index 0de8350..939d259 100644
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -124,7 +124,7 @@ static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
node->port_count = port_count;

- atomic_set(&node->ref_count, 1);
+ refcount_set(&node->ref_count, 1);
INIT_LIST_HEAD(&node->link);

return node;
diff --git a/drivers/firewire/core.h b/drivers/firewire/core.h
index e1480ff6..c07962e 100644
--- a/drivers/firewire/core.h
+++ b/drivers/firewire/core.h
@@ -12,7 +12,7 @@
#include <linux/slab.h>
#include <linux/types.h>

-#include <linux/atomic.h>
+#include <linux/refcount.h>

struct device;
struct fw_card;
@@ -184,7 +184,7 @@ struct fw_node {
* local node to this node. */
u8 max_depth:4; /* Maximum depth to any leaf node */
u8 max_hops:4; /* Max hops in this sub tree */
- atomic_t ref_count;
+ refcount_t ref_count;

/* For serializing node topology into a list. */
struct list_head link;
@@ -197,14 +197,14 @@ struct fw_node {

static inline struct fw_node *fw_node_get(struct fw_node *node)
{
- atomic_inc(&node->ref_count);
+ refcount_inc(&node->ref_count);

return node;
}

static inline void fw_node_put(struct fw_node *node)
{
- if (atomic_dec_and_test(&node->ref_count))
+ if (refcount_dec_and_test(&node->ref_count))
kfree(node);
}

--
2.7.4