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ksmbd: fix race condition between session lookup and expire

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commit 53ff5cf891 upstream.

 Thread A                        +  Thread B
 ksmbd_session_lookup            |  smb2_sess_setup
   sess = xa_load                |
                                 |
                                 |    xa_erase(&conn->sessions, sess->id);
                                 |
                                 |    ksmbd_session_destroy(sess) --> kfree(sess)
                                 |
   // UAF!                       |
   sess->last_active = jiffies   |
                                 +

This patch add rwsem to fix race condition between ksmbd_session_lookup
and ksmbd_expire_session.

Reported-by: luosili <rootlab@huawei.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Namjae Jeon
2023-10-04 18:25:01 +09:00
committed by Greg Kroah-Hartman
parent 64301a9354
commit a2ca5fd3db
3 changed files with 10 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
fs/smb/server/connection.c
View File

@@ -84,6 +84,8 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
spin_lock_init(&conn->llist_lock); spin_lock_init(&conn->llist_lock);
INIT_LIST_HEAD(&conn->lock_list); INIT_LIST_HEAD(&conn->lock_list);
init_rwsem(&conn->session_lock);
down_write(&conn_list_lock); down_write(&conn_list_lock);
list_add(&conn->conns_list, &conn_list); list_add(&conn->conns_list, &conn_list);
up_write(&conn_list_lock); up_write(&conn_list_lock);

1
fs/smb/server/connection.h
View File

@@ -50,6 +50,7 @@ struct ksmbd_conn {
struct nls_table *local_nls; struct nls_table *local_nls;
struct unicode_map *um; struct unicode_map *um;
struct list_head conns_list; struct list_head conns_list;
struct rw_semaphore session_lock;
/* smb session 1 per user */ /* smb session 1 per user */
struct xarray sessions; struct xarray sessions;
unsigned long last_active; unsigned long last_active;

10
fs/smb/server/mgmt/user_session.c
View File

@@ -183,7 +183,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
unsigned long id; unsigned long id;
struct ksmbd_session *sess; struct ksmbd_session *sess;
down_write(&sessions_table_lock); down_write(&conn->session_lock);
xa_for_each(&conn->sessions, id, sess) { xa_for_each(&conn->sessions, id, sess) {
if (sess->state != SMB2_SESSION_VALID || if (sess->state != SMB2_SESSION_VALID ||
time_after(jiffies, time_after(jiffies,
@@ -194,7 +194,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
continue; continue;
} }
} }
up_write(&sessions_table_lock); up_write(&conn->session_lock);
} }
int ksmbd_session_register(struct ksmbd_conn *conn, int ksmbd_session_register(struct ksmbd_conn *conn,
@@ -236,7 +236,9 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
} }
} }
} }
up_write(&sessions_table_lock);
down_write(&conn->session_lock);
xa_for_each(&conn->sessions, id, sess) { xa_for_each(&conn->sessions, id, sess) {
unsigned long chann_id; unsigned long chann_id;
struct channel *chann; struct channel *chann;
@@ -253,7 +255,7 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
ksmbd_session_destroy(sess); ksmbd_session_destroy(sess);
} }
} }
up_write(&sessions_table_lock); up_write(&conn->session_lock);
} }
struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn, struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn,
@@ -261,9 +263,11 @@ struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn,
{ {
struct ksmbd_session *sess; struct ksmbd_session *sess;
down_read(&conn->session_lock);
sess = xa_load(&conn->sessions, id); sess = xa_load(&conn->sessions, id);
if (sess) if (sess)
sess->last_active = jiffies; sess->last_active = jiffies;
up_read(&conn->session_lock);
return sess; return sess;
} }