From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30D0F1E3DF3; Mon, 21 Oct 2024 10:41:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729507271; cv=none; b=Bg0zsq/E5XiJuq0T9LrLzmw7rD8jgg3B6ScggCGdEqXT3jJWIqRasBn/QwjlEZeMZxCQv2YjMrFcAIXtEBdcSa/wCbN3KQDaSIH6NTfM/rBeBh0FKTFaodyNeFSFc0NOOmZ81hBvCXukDPYqWnneCU4dlPx3EPFjwD6d0TSX/DY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729507271; c=relaxed/simple; bh=ObphCfngXRde0m7QoMtDMyVH9tEodP5V1TtpbQ6UYAU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pbA0293iYrKXlySJxdkd3CE6Kr5uOba0LEXr3f0rjXzeVhiZiSFHJZTn1OeIXXjuEs/4WXS9w0KTGK77qHsy/xku3XZvlT3PxQqsxcX6NYbb7zT+xCPq5CE/B8KHy9fvr1WUBYl96aCC4yAUcdOcqOCsO01LbLU4XrU4efACFwc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=kOtjms3W; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kOtjms3W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C51DC4CEC3; Mon, 21 Oct 2024 10:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1729507270; bh=ObphCfngXRde0m7QoMtDMyVH9tEodP5V1TtpbQ6UYAU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kOtjms3W/zeMhuLqpR34pXIQLcc/ndIQQdsIGed+k2boEfj4ox5kOdCwHhZpqxtHK qv2advE87ItpjOdsN7pF+0AC/pmH90EojIwQkfkAItU6l7IHZ3HXXpwi4L9qnUQTie pIsFghKQA1C/nInv8g7ZMYorcy6ZrwcDcDIDo/lg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Namjae Jeon , Steve French , zdi-disclosures@trendmicro.com Subject: [PATCH 6.1 03/91] ksmbd: fix user-after-free from session log off Date: Mon, 21 Oct 2024 12:24:17 +0200 Message-ID: <20241021102249.930971205@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241021102249.791942892@linuxfoundation.org> References: <20241021102249.791942892@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon commit 7aa8804c0b67b3cb263a472d17f2cb50d7f1a930 upstream. There is racy issue between smb2 session log off and smb2 session setup. It will cause user-after-free from session log off. This add session_lock when setting SMB2_SESSION_EXPIRED and referece count to session struct not to free session while it is being used. Cc: stable@vger.kernel.org # v5.15+ Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-25282 Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/smb/server/mgmt/user_session.c | 26 +++++++++++++++++++++----- fs/smb/server/mgmt/user_session.h | 4 ++++ fs/smb/server/server.c | 2 ++ fs/smb/server/smb2pdu.c | 8 +++++++- 4 files changed, 34 insertions(+), 6 deletions(-) --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -176,9 +176,10 @@ static void ksmbd_expire_session(struct down_write(&conn->session_lock); xa_for_each(&conn->sessions, id, sess) { - if (sess->state != SMB2_SESSION_VALID || - time_after(jiffies, - sess->last_active + SMB2_SESSION_TIMEOUT)) { + if (atomic_read(&sess->refcnt) == 0 && + (sess->state != SMB2_SESSION_VALID || + time_after(jiffies, + sess->last_active + SMB2_SESSION_TIMEOUT))) { xa_erase(&conn->sessions, sess->id); hash_del(&sess->hlist); ksmbd_session_destroy(sess); @@ -268,8 +269,6 @@ struct ksmbd_session *ksmbd_session_look down_read(&sessions_table_lock); sess = __session_lookup(id); - if (sess) - sess->last_active = jiffies; up_read(&sessions_table_lock); return sess; @@ -288,6 +287,22 @@ struct ksmbd_session *ksmbd_session_look return sess; } +void ksmbd_user_session_get(struct ksmbd_session *sess) +{ + atomic_inc(&sess->refcnt); +} + +void ksmbd_user_session_put(struct ksmbd_session *sess) +{ + if (!sess) + return; + + if (atomic_read(&sess->refcnt) <= 0) + WARN_ON(1); + else + atomic_dec(&sess->refcnt); +} + struct preauth_session *ksmbd_preauth_session_alloc(struct ksmbd_conn *conn, u64 sess_id) { @@ -356,6 +371,7 @@ static struct ksmbd_session *__session_c xa_init(&sess->rpc_handle_list); sess->sequence_number = 1; rwlock_init(&sess->tree_conns_lock); + atomic_set(&sess->refcnt, 1); ret = __init_smb2_session(sess); if (ret) --- a/fs/smb/server/mgmt/user_session.h +++ b/fs/smb/server/mgmt/user_session.h @@ -61,6 +61,8 @@ struct ksmbd_session { struct ksmbd_file_table file_table; unsigned long last_active; rwlock_t tree_conns_lock; + + atomic_t refcnt; }; static inline int test_session_flag(struct ksmbd_session *sess, int bit) @@ -101,4 +103,6 @@ void ksmbd_release_tree_conn_id(struct k int ksmbd_session_rpc_open(struct ksmbd_session *sess, char *rpc_name); void ksmbd_session_rpc_close(struct ksmbd_session *sess, int id); int ksmbd_session_rpc_method(struct ksmbd_session *sess, int id); +void ksmbd_user_session_get(struct ksmbd_session *sess); +void ksmbd_user_session_put(struct ksmbd_session *sess); #endif /* __USER_SESSION_MANAGEMENT_H__ */ --- a/fs/smb/server/server.c +++ b/fs/smb/server/server.c @@ -238,6 +238,8 @@ static void __handle_ksmbd_work(struct k } while (is_chained == true); send: + if (work->sess) + ksmbd_user_session_put(work->sess); if (work->tcon) ksmbd_tree_connect_put(work->tcon); smb3_preauth_hash_rsp(work); --- a/fs/smb/server/smb2pdu.c +++ b/fs/smb/server/smb2pdu.c @@ -604,8 +604,10 @@ int smb2_check_user_session(struct ksmbd /* Check for validity of user session */ work->sess = ksmbd_session_lookup_all(conn, sess_id); - if (work->sess) + if (work->sess) { + ksmbd_user_session_get(work->sess); return 1; + } ksmbd_debug(SMB, "Invalid user session, Uid %llu\n", sess_id); return -ENOENT; } @@ -1759,6 +1761,7 @@ int smb2_sess_setup(struct ksmbd_work *w } conn->binding = true; + ksmbd_user_session_get(sess); } else if ((conn->dialect < SMB30_PROT_ID || server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL) && (req->Flags & SMB2_SESSION_REQ_FLAG_BINDING)) { @@ -1785,6 +1788,7 @@ int smb2_sess_setup(struct ksmbd_work *w } conn->binding = false; + ksmbd_user_session_get(sess); } work->sess = sess; @@ -2240,7 +2244,9 @@ int smb2_session_logoff(struct ksmbd_wor } 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;