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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 06452C54FCB for ; Thu, 23 Apr 2020 22:49:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D9F6520736 for ; Thu, 23 Apr 2020 22:49:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727957AbgDWWtw (ORCPT ); Thu, 23 Apr 2020 18:49:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37480 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726057AbgDWWtv (ORCPT ); Thu, 23 Apr 2020 18:49:51 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AF36C09B042; Thu, 23 Apr 2020 15:49:51 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 4FE8F127E5B39; Thu, 23 Apr 2020 15:49:50 -0700 (PDT) Date: Thu, 23 Apr 2020 15:49:49 -0700 (PDT) Message-Id: <20200423.154949.459034580485896359.davem@davemloft.net> To: xiyuyang19@fudan.edu.cn Cc: andrew.hendry@gmail.com, kuba@kernel.org, gregkh@linuxfoundation.org, edumazet@google.com, allison@lohutok.net, tglx@linutronix.de, linux-x25@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, yuanxzhang@fudan.edu.cn, kjlu@umn.edu, tanxin.ctf@gmail.com Subject: Re: [PATCH] net/x25: Fix x25_neigh refcnt leak when reveiving frame From: David Miller In-Reply-To: <1587618786-13481-1-git-send-email-xiyuyang19@fudan.edu.cn> References: <1587618786-13481-1-git-send-email-xiyuyang19@fudan.edu.cn> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 23 Apr 2020 15:49:50 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xiyu Yang Date: Thu, 23 Apr 2020 13:13:03 +0800 > x25_lapb_receive_frame() invokes x25_get_neigh(), which returns a > reference of the specified x25_neigh object to "nb" with increased > refcnt. > > When x25_lapb_receive_frame() returns, local variable "nb" becomes > invalid, so the refcount should be decreased to keep refcount balanced. > > The reference counting issue happens in one path of > x25_lapb_receive_frame(). When pskb_may_pull() returns false, the > function forgets to decrease the refcnt increased by x25_get_neigh(), > causing a refcnt leak. > > Fix this issue by calling x25_neigh_put() when pskb_may_pull() returns > false. > > Signed-off-by: Xiyu Yang > Signed-off-by: Xin Tan Applied and queued up for -stable, thanks.