diff options
| author | Namjae Jeon <linkinjeon@kernel.org> | 2025-03-27 21:22:51 +0900 |
|---|---|---|
| committer | Steve French <stfrench@microsoft.com> | 2025-04-01 00:04:21 -0500 |
| commit | fa4cdb8cbca7d6cb6aa13e4d8d83d1103f6345db (patch) | |
| tree | 0c30a908ab1ed26725859df5a3f18493a2691b64 /fs | |
| parent | f64a72bc767f6e9ddb18fdacaeb99708c4810ada (diff) | |
ksmbd: fix session use-after-free in multichannel connection
There is a race condition between session setup and
ksmbd_sessions_deregister. The session can be freed before the connection
is added to channel list of session.
This patch check reference count of session before freeing it.
Cc: stable@vger.kernel.org
Reported-by: Sean Heelan <seanheelan@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/smb/server/auth.c | 4 | ||||
| -rw-r--r-- | fs/smb/server/mgmt/user_session.c | 14 | ||||
| -rw-r--r-- | fs/smb/server/smb2pdu.c | 7 |
3 files changed, 14 insertions, 11 deletions
diff --git a/fs/smb/server/auth.c b/fs/smb/server/auth.c index 00b31cf86462..83caa3849749 100644 --- a/fs/smb/server/auth.c +++ b/fs/smb/server/auth.c @@ -1016,9 +1016,9 @@ static int ksmbd_get_encryption_key(struct ksmbd_work *work, __u64 ses_id, ses_enc_key = enc ? sess->smb3encryptionkey : sess->smb3decryptionkey; - if (enc) - ksmbd_user_session_get(sess); memcpy(key, ses_enc_key, SMB3_ENC_DEC_KEY_SIZE); + if (!enc) + ksmbd_user_session_put(sess); return 0; } diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c index 53d308f331af..7690f0187dac 100644 --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -181,7 +181,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn) down_write(&sessions_table_lock); down_write(&conn->session_lock); xa_for_each(&conn->sessions, id, sess) { - if (atomic_read(&sess->refcnt) == 0 && + if (atomic_read(&sess->refcnt) <= 1 && (sess->state != SMB2_SESSION_VALID || time_after(jiffies, sess->last_active + SMB2_SESSION_TIMEOUT))) { @@ -233,7 +233,8 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn) down_write(&conn->session_lock); xa_erase(&conn->sessions, sess->id); up_write(&conn->session_lock); - ksmbd_session_destroy(sess); + if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } } } @@ -252,7 +253,8 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn) if (xa_empty(&sess->ksmbd_chann_list)) { xa_erase(&conn->sessions, sess->id); hash_del(&sess->hlist); - ksmbd_session_destroy(sess); + if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } } up_write(&conn->session_lock); @@ -328,8 +330,8 @@ void ksmbd_user_session_put(struct ksmbd_session *sess) if (atomic_read(&sess->refcnt) <= 0) WARN_ON(1); - else - atomic_dec(&sess->refcnt); + else if (atomic_dec_and_test(&sess->refcnt)) + ksmbd_session_destroy(sess); } struct preauth_session *ksmbd_preauth_session_alloc(struct ksmbd_conn *conn, @@ -436,7 +438,7 @@ static struct ksmbd_session *__session_create(int protocol) xa_init(&sess->rpc_handle_list); sess->sequence_number = 1; rwlock_init(&sess->tree_conns_lock); - atomic_set(&sess->refcnt, 1); + atomic_set(&sess->refcnt, 2); ret = __init_smb2_session(sess); if (ret) diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c index 4ddf4300371b..f3ca33d3b69a 100644 --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -2235,13 +2235,14 @@ int smb2_session_logoff(struct ksmbd_work *work) return -ENOENT; } - ksmbd_destroy_file_table(&sess->file_table); down_write(&conn->session_lock); sess->state = SMB2_SESSION_EXPIRED; up_write(&conn->session_lock); - ksmbd_free_user(sess->user); - sess->user = NULL; + if (sess->user) { + ksmbd_free_user(sess->user); + sess->user = NULL; + } ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_NEGOTIATE); rsp->StructureSize = cpu_to_le16(4); |