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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C3BDDC433E0 for ; Thu, 14 May 2020 14:54:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD70920643 for ; Thu, 14 May 2020 14:54:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727067AbgENOyb (ORCPT ); Thu, 14 May 2020 10:54:31 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:59192 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726051AbgENOyb (ORCPT ); Thu, 14 May 2020 10:54:31 -0400 Received: from callcc.thunk.org (pool-100-0-195-244.bstnma.fios.verizon.net [100.0.195.244]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 04EEsFEX007807 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 14 May 2020 10:54:16 -0400 Received: by callcc.thunk.org (Postfix, from userid 15806) id 84958420304; Thu, 14 May 2020 10:54:15 -0400 (EDT) Date: Thu, 14 May 2020 10:54:15 -0400 From: "Theodore Y. Ts'o" To: Xiyu Yang Cc: Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, yuanxzhang@fudan.edu.cn, kjlu@umn.edu, Xin Tan Subject: Re: [PATCH] ext4: Fix buffer_head refcnt leak when ext4_iget() fails Message-ID: <20200514145415.GU1596452@mit.edu> References: <1587618568-13418-1-git-send-email-xiyuyang19@fudan.edu.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1587618568-13418-1-git-send-email-xiyuyang19@fudan.edu.cn> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 23, 2020 at 01:09:27PM +0800, Xiyu Yang wrote: > ext4_orphan_get() invokes ext4_read_inode_bitmap(), which returns a > reference of the specified buffer_head object to "bitmap_bh" with > increased refcnt. > > When ext4_orphan_get() returns, local variable "bitmap_bh" becomes > invalid, so the refcount should be decreased to keep refcount balanced. > > The reference counting issue happens in one exception handling path of > ext4_orphan_get(). When ext4_iget() fails, the function forgets to > decrease the refcnt increased by ext4_read_inode_bitmap(), causing a > refcnt leak. > > Fix this issue by calling brelse() when ext4_iget() fails. > > Signed-off-by: Xiyu Yang > Signed-off-by: Xin Tan Applied, thanks. - Ted