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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 24 +++++++++++------------
 drivers/net/ethernet/mellanox/mlx5/core/fs_core.h |  3 ++-
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c 
b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index 2478516..4f74d15 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -163,7 +163,7 @@ static void tree_init_node(struct fs_node *node,
                           unsigned int refcount,
                           void (*remove_func)(struct fs_node *))
 {
-       atomic_set(&node->refcount, refcount);
+       refcount_set(&node->refcount, refcount);
        INIT_LIST_HEAD(&node->list);
        INIT_LIST_HEAD(&node->children);
        mutex_init(&node->lock);
@@ -173,7 +173,7 @@ static void tree_init_node(struct fs_node *node,
 static void tree_add_node(struct fs_node *node, struct fs_node *parent)
 {
        if (parent)
-               atomic_inc(&parent->refcount);
+               refcount_inc(&parent->refcount);
        node->parent = parent;
 
        /* Parent is the root */
@@ -185,7 +185,7 @@ static void tree_add_node(struct fs_node *node, struct 
fs_node *parent)
 
 static void tree_get_node(struct fs_node *node)
 {
-       atomic_inc(&node->refcount);
+       refcount_inc(&node->refcount);
 }
 
 static void nested_lock_ref_node(struct fs_node *node,
@@ -193,7 +193,7 @@ static void nested_lock_ref_node(struct fs_node *node,
 {
        if (node) {
                mutex_lock_nested(&node->lock, class);
-               atomic_inc(&node->refcount);
+               refcount_inc(&node->refcount);
        }
 }
 
@@ -201,14 +201,14 @@ static void lock_ref_node(struct fs_node *node)
 {
        if (node) {
                mutex_lock(&node->lock);
-               atomic_inc(&node->refcount);
+               refcount_inc(&node->refcount);
        }
 }
 
 static void unlock_ref_node(struct fs_node *node)
 {
        if (node) {
-               atomic_dec(&node->refcount);
+               refcount_dec(&node->refcount);
                mutex_unlock(&node->lock);
        }
 }
@@ -218,7 +218,7 @@ static void tree_put_node(struct fs_node *node)
        struct fs_node *parent_node = node->parent;
 
        lock_ref_node(parent_node);
-       if (atomic_dec_and_test(&node->refcount)) {
+       if (refcount_dec_and_test(&node->refcount)) {
                if (parent_node)
                        list_del_init(&node->list);
                if (node->remove_func)
@@ -233,8 +233,8 @@ static void tree_put_node(struct fs_node *node)
 
 static int tree_remove_node(struct fs_node *node)
 {
-       if (atomic_read(&node->refcount) > 1) {
-               atomic_dec(&node->refcount);
+       if (refcount_read(&node->refcount) > 1) {
+               refcount_dec(&node->refcount);
                return -EEXIST;
        }
        tree_put_node(node);
@@ -982,7 +982,7 @@ static void destroy_flow_handle(struct fs_fte *fte,
                                int i)
 {
        for (; --i >= 0;) {
-               if (atomic_dec_and_test(&handle->rule[i]->node.refcount)) {
+               if (refcount_dec_and_test(&handle->rule[i]->node.refcount)) {
                        fte->dests_size--;
                        list_del(&handle->rule[i]->node.list);
                        kfree(handle->rule[i]);
@@ -1013,7 +1013,7 @@ create_flow_handle(struct fs_fte *fte,
                if (dest) {
                        rule = find_flow_rule(fte, dest + i);
                        if (rule) {
-                               atomic_inc(&rule->node.refcount);
+                               refcount_inc(&rule->node.refcount);
                                goto rule_found;
                        }
                }
@@ -1282,7 +1282,7 @@ static struct mlx5_flow_handle *add_rule_fg(struct 
mlx5_flow_group *fg,
        list_add(&fte->node.list, prev);
 add_rules:
        for (i = 0; i < handle->num_rules; i++) {
-               if (atomic_read(&handle->rule[i]->node.refcount) == 1)
+               if (refcount_read(&handle->rule[i]->node.refcount) == 1)
                        tree_add_node(&handle->rule[i]->node, &fte->node);
        }
 unlock_fte:
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h 
b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h
index 8e668c6..86bc743b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h
@@ -33,6 +33,7 @@
 #ifndef _MLX5_FS_CORE_
 #define _MLX5_FS_CORE_
 
+#include <linux/refcount.h>
 #include <linux/mlx5/fs.h>
 
 enum fs_node_type {
@@ -80,7 +81,7 @@ struct fs_node {
        struct fs_node          *root;
        /* lock the node for writing and traversing */
        struct mutex            lock;
-       atomic_t                refcount;
+       refcount_t              refcount;
        void                    (*remove_func)(struct fs_node *);
 };
 
-- 
2.7.4

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