ksmbd: fix missing chann_lock while iterating session channel list

Add chann_lock while iterating ksmbd_chann_list in show_proc_session() and
show_proc_sessions(). This will prevents a race condition with concurrent
channel list modifications.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c
index 8c2b14ea7b0ec6ab6e8a72eb36020906ea003ca3..c35083f576c32289f2b7d31d55d79c6a51bc9de7 100644 (file)
--- a/fs/smb/server/mgmt/user_session.c
+++ b/fs/smb/server/mgmt/user_session.c
@@ -91,6 +91,7 @@ static int show_proc_session(struct seq_file *m, void *v)
        ksmbd_user_session_get(sess);
 
        i = 0;
+       down_read(&sess->chann_lock);
        xa_for_each(&sess->ksmbd_chann_list, id, chan) {
 #if IS_ENABLED(CONFIG_IPV6)
                if (chan->conn->inet_addr)
@@ -129,6 +130,7 @@ static int show_proc_session(struct seq_file *m, void *v)
                }
                i++;
        }
+       up_read(&sess->chann_lock);
 
        seq_printf(m, "%-20s\t%d\n", "channels", i);
 
@@ -205,22 +207,24 @@ static int show_proc_sessions(struct seq_file *m, void *v)
 
        down_read(&sessions_table_lock);
        hash_for_each(sessions_table, i, session, hlist) {
+               down_read(&session->chann_lock);
                xa_for_each(&session->ksmbd_chann_list, id, chan) {
-               down_read(&chan->conn->session_lock);
-               ksmbd_user_session_get(session);
-
-               if (chan->conn->inet_addr)
-                       seq_printf(m, " %-40pI4", &chan->conn->inet_addr);
-               else
-                       seq_printf(m, " %-40pI6c", &chan->conn->inet6_addr);
-               seq_printf(m, " %-15s %-10llu %-10s\n",
-                          session_user_name(session),
-                          session->id,
-                          session_state_string(session));
-
-               ksmbd_user_session_put(session);
-               up_read(&chan->conn->session_lock);
-       }
+                       down_read(&chan->conn->session_lock);
+                       ksmbd_user_session_get(session);
+
+                       if (chan->conn->inet_addr)
+                               seq_printf(m, " %-40pI4", &chan->conn->inet_addr);
+                       else
+                               seq_printf(m, " %-40pI6c", &chan->conn->inet6_addr);
+                       seq_printf(m, " %-15s %-10llu %-10s\n",
+                                  session_user_name(session),
+                                  session->id,
+                                  session_state_string(session));
+
+                       ksmbd_user_session_put(session);
+                       up_read(&chan->conn->session_lock);
+               }
+               up_read(&session->chann_lock);
        }
        up_read(&sessions_table_lock);
        return 0;