[PATCH] net: core: devlink.c: Hold devlink->lock from the beginning of devlink_dpipe_table_register()

From: Madhuparna Bhowmik <redacted>

devlink_dpipe_table_find() should be called under either
rcu_read_lock() or devlink->lock. devlink_dpipe_table_register()
calls devlink_dpipe_table_find() without holding the lock
and acquires it later. Therefore hold the devlink->lock
from the beginning of devlink_dpipe_table_register().

Suggested-by: Jiri Pirko <redacted>
Signed-off-by: Madhuparna Bhowmik <redacted>
---
 net/core/devlink.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 3e8c94155d93..ba9dd8cb98c3 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -6840,22 +6840,29 @@ int devlink_dpipe_table_register(struct devlink *devlink,
 {
 	struct devlink_dpipe_table *table;
 
-	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name))
+	mutex_lock(&devlink->lock);
+
+	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name)) {
+		mutex_unlock(&devlink->lock);
 		return -EEXIST;
+	}
 
-	if (WARN_ON(!table_ops->size_get))
+	if (WARN_ON(!table_ops->size_get)) {
+		mutex_unlock(&devlink->lock);
 		return -EINVAL;
+	}
 
 	table = kzalloc(sizeof(*table), GFP_KERNEL);
-	if (!table)
+	if (!table) {
+		mutex_unlock(&devlink->lock);
 		return -ENOMEM;
+	}
 
 	table->name = table_name;
 	table->table_ops = table_ops;
 	table->priv = priv;
 	table->counter_control_extern = counter_control_extern;
 
-	mutex_lock(&devlink->lock);
 	list_add_tail_rcu(&table->list, &devlink->dpipe_table_list);
 	mutex_unlock(&devlink->lock);
 	return 0;

-- 
2.17.1

Sat, Feb 22, 2020 at 07:52:34AM CET, madhuparnabhowmik10@gmail.com wrote:

Please use "goto unlock" instead of unlocking on multiple places.

		return -ENOMEM;
+	}

	table->name = table_name;
	table->table_ops = table_ops;
	table->priv = priv;
	table->counter_control_extern = counter_control_extern;

-	mutex_lock(&devlink->lock);
	list_add_tail_rcu(&table->list, &devlink->dpipe_table_list);
	mutex_unlock(&devlink->lock);
	return 0;
-- 
2.17.1

On Sun, Feb 23, 2020 at 07:43:29AM +0100, Jiri Pirko wrote:

Sat, Feb 22, 2020 at 07:52:34AM CET, madhuparnabhowmik10@gmail.com wrote:

quoted

From: Madhuparna Bhowmik <redacted>

devlink_dpipe_table_find() should be called under either
rcu_read_lock() or devlink->lock. devlink_dpipe_table_register()
calls devlink_dpipe_table_find() without holding the lock
and acquires it later. Therefore hold the devlink->lock
from the beginning of devlink_dpipe_table_register().

Suggested-by: Jiri Pirko <redacted>
Signed-off-by: Madhuparna Bhowmik <redacted>
---
net/core/devlink.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 3e8c94155d93..ba9dd8cb98c3 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -6840,22 +6840,29 @@ int devlink_dpipe_table_register(struct devlink *devlink,

{
	struct devlink_dpipe_table *table;

-	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name))
+	mutex_lock(&devlink->lock);
+
+	if (devlink_dpipe_table_find(&devlink->dpipe_table_list, table_name)) {
+		mutex_unlock(&devlink->lock);
		return -EEXIST;
+	}

-	if (WARN_ON(!table_ops->size_get))
+	if (WARN_ON(!table_ops->size_get)) {
+		mutex_unlock(&devlink->lock);
		return -EINVAL;
+	}

	table = kzalloc(sizeof(*table), GFP_KERNEL);
-	if (!table)
+	if (!table) {
+		mutex_unlock(&devlink->lock);

Please use "goto unlock" instead of unlocking on multiple places.

Sure, I have sent a new patch.
Thank you,
Madhuparna

quoted

		return -ENOMEM;
+	}

	table->name = table_name;
	table->table_ops = table_ops;
	table->priv = priv;
	table->counter_control_extern = counter_control_extern;

-	mutex_lock(&devlink->lock);
	list_add_tail_rcu(&table->list, &devlink->dpipe_table_list);
	mutex_unlock(&devlink->lock);
	return 0;
-- 
2.17.1