batman-adv: Check return value of try_module_get

New operations should not be started when they need an increased module
reference counter and try_module_get failed.

This patch addresses Coverity #712284: Unchecked return value

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

4 files changed, 12 insertions, 18 deletions

diff --git a/net/batman-adv/debugfs.c b/net/batman-adv/debugfs.c
index 391d4fb2026f..bd032bc4e262 100644
--- a/net/batman-adv/debugfs.c
+++ b/net/batman-adv/debugfs.c
@@ -99,15 +99,17 @@ int batadv_debug_log(struct batadv_priv *bat_priv, const char *fmt, ...)
 
 static int batadv_log_open(struct inode *inode, struct file *file)
 {
+        if (!try_module_get(THIS_MODULE))
+                return -EBUSY;
+
         nonseekable_open(inode, file);
         file->private_data = inode->i_private;
-        batadv_inc_module_count();
         return 0;
 }
 
 static int batadv_log_release(struct inode *inode, struct file *file)
 {
-        batadv_dec_module_count();
+        module_put(THIS_MODULE);
         return 0;
 }
 
diff --git a/net/batman-adv/icmp_socket.c b/net/batman-adv/icmp_socket.c
index bde3cf747507..5874c0e84846 100644
--- a/net/batman-adv/icmp_socket.c
+++ b/net/batman-adv/icmp_socket.c
@@ -42,12 +42,16 @@ static int batadv_socket_open(struct inode *inode, struct file *file)
         unsigned int i;
         struct batadv_socket_client *socket_client;
 
+        if (!try_module_get(THIS_MODULE))
+                return -EBUSY;
+
         nonseekable_open(inode, file);
 
         socket_client = kmalloc(sizeof(*socket_client), GFP_KERNEL);
-
-        if (!socket_client)
+        if (!socket_client) {
+                module_put(THIS_MODULE);
                 return -ENOMEM;
+        }
 
         for (i = 0; i < ARRAY_SIZE(batadv_socket_client_hash); i++) {
                 if (!batadv_socket_client_hash[i]) {
@@ -59,6 +63,7 @@ static int batadv_socket_open(struct inode *inode, struct file *file)
         if (i == ARRAY_SIZE(batadv_socket_client_hash)) {
                 pr_err("Error - can't add another packet client: maximum number of clients reached\n");
                 kfree(socket_client);
+                module_put(THIS_MODULE);
                 return -EXFULL;
         }
 
@@ -71,7 +76,6 @@ static int batadv_socket_open(struct inode *inode, struct file *file)
 
         file->private_data = socket_client;
 
-        batadv_inc_module_count();
         return 0;
 }
 
@@ -96,7 +100,7 @@ static int batadv_socket_release(struct inode *inode, struct file *file)
         spin_unlock_bh(&socket_client->lock);
 
         kfree(socket_client);
-        batadv_dec_module_count();
+        module_put(THIS_MODULE);
 
         return 0;
 }
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index a4a337d9af9c..f9bcfa17f50f 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -160,16 +160,6 @@ void batadv_mesh_free(struct net_device *soft_iface)
         atomic_set(&bat_priv->mesh_state, BATADV_MESH_INACTIVE);
 }
 
-void batadv_inc_module_count(void)
-{
-        try_module_get(THIS_MODULE);
-}
-
-void batadv_dec_module_count(void)
-{
-        module_put(THIS_MODULE);
-}
-
 int batadv_is_my_mac(const uint8_t *addr)
 {
         const struct batadv_hard_iface *hard_iface;
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index 5c0be5b13415..9b94f05f8a17 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -150,8 +150,6 @@ extern struct workqueue_struct *batadv_event_workqueue;
 
 int batadv_mesh_init(struct net_device *soft_iface);
 void batadv_mesh_free(struct net_device *soft_iface);
-void batadv_inc_module_count(void);
-void batadv_dec_module_count(void);
 int batadv_is_my_mac(const uint8_t *addr);
 struct batadv_hard_iface *
 batadv_seq_print_text_primary_if_get(struct seq_file *seq);