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 903354C3D7; Wed, 20 Dec 2023 16:17:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LWzNdqmW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1720EC433C7; Wed, 20 Dec 2023 16:17:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1703089072; bh=yy+nZboN2nk7sp/YdNbNe3uOngTJDI/iA9/PMmI+tfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LWzNdqmW1c8ZhnJLkLsbXLnMAdoTF1UFgZcI0zEKpO1FQvHWwW78YDuQ6ETdCHm+4 0j8jj76K8lp7RBfeDmG/EqiHkaTrIkwvlu+71vuzggpDpHuP3eTnDuvI5vngBuBV9L zfnb2k3byxho1i8DlXf9MBL4TS22NJlGEXfi7pyM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, luosili , Namjae Jeon , Steve French Subject: [PATCH 5.15 131/159] ksmbd: fix race condition between session lookup and expire Date: Wed, 20 Dec 2023 17:09:56 +0100 Message-ID: <20231220160937.444129873@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231220160931.251686445@linuxfoundation.org> References: <20231220160931.251686445@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Namjae Jeon [ Upstream commit 53ff5cf89142b978b1a5ca8dc4d4425e6a09745f ] 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 Signed-off-by: Namjae Jeon Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/ksmbd/connection.c | 2 ++ fs/ksmbd/connection.h | 1 + fs/ksmbd/mgmt/user_session.c | 10 +++++++--- 3 files changed, 10 insertions(+), 3 deletions(-) --- a/fs/ksmbd/connection.c +++ b/fs/ksmbd/connection.c @@ -84,6 +84,8 @@ struct ksmbd_conn *ksmbd_conn_alloc(void spin_lock_init(&conn->llist_lock); INIT_LIST_HEAD(&conn->lock_list); + init_rwsem(&conn->session_lock); + down_write(&conn_list_lock); list_add(&conn->conns_list, &conn_list); up_write(&conn_list_lock); --- a/fs/ksmbd/connection.h +++ b/fs/ksmbd/connection.h @@ -50,6 +50,7 @@ struct ksmbd_conn { struct nls_table *local_nls; struct unicode_map *um; struct list_head conns_list; + struct rw_semaphore session_lock; /* smb session 1 per user */ struct xarray sessions; unsigned long last_active; --- a/fs/ksmbd/mgmt/user_session.c +++ b/fs/ksmbd/mgmt/user_session.c @@ -174,7 +174,7 @@ static void ksmbd_expire_session(struct unsigned long id; struct ksmbd_session *sess; - down_write(&sessions_table_lock); + down_write(&conn->session_lock); xa_for_each(&conn->sessions, id, sess) { if (sess->state != SMB2_SESSION_VALID || time_after(jiffies, @@ -185,7 +185,7 @@ static void ksmbd_expire_session(struct continue; } } - up_write(&sessions_table_lock); + up_write(&conn->session_lock); } int ksmbd_session_register(struct ksmbd_conn *conn, @@ -227,7 +227,9 @@ void ksmbd_sessions_deregister(struct ks } } } + up_write(&sessions_table_lock); + down_write(&conn->session_lock); xa_for_each(&conn->sessions, id, sess) { unsigned long chann_id; struct channel *chann; @@ -244,7 +246,7 @@ void ksmbd_sessions_deregister(struct ks ksmbd_session_destroy(sess); } } - up_write(&sessions_table_lock); + up_write(&conn->session_lock); } struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn, @@ -252,9 +254,11 @@ struct ksmbd_session *ksmbd_session_look { struct ksmbd_session *sess; + down_read(&conn->session_lock); sess = xa_load(&conn->sessions, id); if (sess) sess->last_active = jiffies; + up_read(&conn->session_lock); return sess; }