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 fs_node.refcount is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: David Windsor <dwindsor@xxxxxxxxx>
Reviewed-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlx5/core/fs_core.c | 28 +++++++++++------------
drivers/net/ethernet/mellanox/mlx5/core/fs_core.h | 3 ++-
2 files changed, 16 insertions(+), 15 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
index f77e496..c7fa1389 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
@@ -188,7 +188,7 @@ static void tree_init_node(struct fs_node *node,
void (*del_hw_func)(struct fs_node *),
void (*del_sw_func)(struct fs_node *))
{
- atomic_set(&node->refcount, 1);
+ refcount_set(&node->refcount, 1);
INIT_LIST_HEAD(&node->list);
INIT_LIST_HEAD(&node->children);
init_rwsem(&node->lock);
@@ -200,7 +200,7 @@ 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 */
@@ -212,7 +212,7 @@ static void tree_add_node(struct fs_node *node, struct fs_node *parent)
static int tree_get_node(struct fs_node *node)
{
- return atomic_add_unless(&node->refcount, 1, 0);
+ return refcount_inc_not_zero(&node->refcount);
}
static void nested_down_read_ref_node(struct fs_node *node,
@@ -220,7 +220,7 @@ static void nested_down_read_ref_node(struct fs_node *node,
{
if (node) {
down_read_nested(&node->lock, class);
- atomic_inc(&node->refcount);
+ refcount_inc(&node->refcount);
}
}
@@ -229,7 +229,7 @@ static void nested_down_write_ref_node(struct fs_node *node,
{
if (node) {
down_write_nested(&node->lock, class);
- atomic_inc(&node->refcount);
+ refcount_inc(&node->refcount);
}
}
@@ -237,19 +237,19 @@ static void down_write_ref_node(struct fs_node *node)
{
if (node) {
down_write(&node->lock);
- atomic_inc(&node->refcount);
+ refcount_inc(&node->refcount);
}
}
static void up_read_ref_node(struct fs_node *node)
{
- atomic_dec(&node->refcount);
+ refcount_dec(&node->refcount);
up_read(&node->lock);
}
static void up_write_ref_node(struct fs_node *node)
{
- atomic_dec(&node->refcount);
+ refcount_dec(&node->refcount);
up_write(&node->lock);
}
@@ -257,7 +257,7 @@ static void tree_put_node(struct fs_node *node)
{
struct fs_node *parent_node = node->parent;
- if (atomic_dec_and_test(&node->refcount)) {
+ if (refcount_dec_and_test(&node->refcount)) {
if (node->del_hw_func)
node->del_hw_func(node);
if (parent_node) {
@@ -280,8 +280,8 @@ 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);
@@ -1184,7 +1184,7 @@ 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]);
@@ -1215,7 +1215,7 @@ 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;
}
}
@@ -1466,7 +1466,7 @@ static struct mlx5_flow_handle *add_rule_fg(struct mlx5_flow_group *fg,
trace_mlx5_fs_set_fte(fte, false);
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);
trace_mlx5_fs_add_rule(handle->rule[i]);
}
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h b/drivers/net/ethernet/mellanox/mlx5/core/fs_core.h
index 80f6f3c7..397d24a 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>
#include <linux/rhashtable.h>
@@ -84,7 +85,7 @@ struct fs_node {
struct fs_node *root;
/* lock the node for writing and traversing */
struct rw_semaphore lock;
- atomic_t refcount;
+ refcount_t refcount;
bool active;
void (*del_hw_func)(struct fs_node *);
void (*del_sw_func)(struct fs_node *);
--
2.7.4
--
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