From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04DC3C47082 for ; Mon, 31 May 2021 14:30:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC8E6613AE for ; Mon, 31 May 2021 14:30:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232640AbhEaOcY (ORCPT ); Mon, 31 May 2021 10:32:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:55720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233118AbhEaNya (ORCPT ); Mon, 31 May 2021 09:54:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2774061439; Mon, 31 May 2021 13:33:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622468027; bh=IQ7IhCWeAmbY4PS5fgPbkHkaNBhyHOKfgSAxpYDpQB0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K+BVNwDw2VnC81GDOBi7Z4Ox3buYMbUIGeNbroSM5Buz3Dkka5o+uJUEY8Tf22Yz1 craLb+4288r/QX9Dsnu5bJiReA+0Y3cwguyNASs9p4AGiZDZRpR7hpSBY8gtAJm/Oa Xv7Ij4TxHE1LYhTWEHUsN4UWG3x/lqxY/OG2jz8Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thadeu Lima de Souza Cascardo , Marcel Holtmann Subject: [PATCH 5.10 090/252] Bluetooth: cmtp: fix file refcount when cmtp_attach_device fails Date: Mon, 31 May 2021 15:12:35 +0200 Message-Id: <20210531130701.027736633@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130657.971257589@linuxfoundation.org> References: <20210531130657.971257589@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thadeu Lima de Souza Cascardo commit 8da3a0b87f4f1c3a3bbc4bfb78cf68476e97d183 upstream. When cmtp_attach_device fails, cmtp_add_connection returns the error value which leads to the caller to doing fput through sockfd_put. But cmtp_session kthread, which is stopped in this path will also call fput, leading to a potential refcount underflow or a use-after-free. Add a refcount before we signal the kthread to stop. The kthread will try to grab the cmtp_session_sem mutex before doing the fput, which is held when get_file is called, so there should be no races there. Reported-by: Ryota Shiga Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Marcel Holtmann Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/cmtp/core.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/bluetooth/cmtp/core.c +++ b/net/bluetooth/cmtp/core.c @@ -392,6 +392,11 @@ int cmtp_add_connection(struct cmtp_conn if (!(session->flags & BIT(CMTP_LOOPBACK))) { err = cmtp_attach_device(session); if (err < 0) { + /* Caller will call fput in case of failure, and so + * will cmtp_session kthread. + */ + get_file(session->sock->file); + atomic_inc(&session->terminate); wake_up_interruptible(sk_sleep(session->sock->sk)); up_write(&cmtp_session_sem);