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=-11.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 CCE6EC433EF for ; Mon, 6 Sep 2021 16:51:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABC196103D for ; Mon, 6 Sep 2021 16:51:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236271AbhIFQwz (ORCPT ); Mon, 6 Sep 2021 12:52:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234037AbhIFQwx (ORCPT ); Mon, 6 Sep 2021 12:52:53 -0400 Received: from mail-lj1-x22f.google.com (mail-lj1-x22f.google.com [IPv6:2a00:1450:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21DD2C061575; Mon, 6 Sep 2021 09:51:48 -0700 (PDT) Received: by mail-lj1-x22f.google.com with SMTP id s3so12227273ljp.11; Mon, 06 Sep 2021 09:51:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language :from:to:cc:references:in-reply-to:content-transfer-encoding; bh=HDKqg2pWAZz4uZmdk0aehi0Cj5oQsrM+ze2oyg6/ka8=; b=IYR+4FWNbNbEfelaudwpyUei6jY6Xb0GzO8X/1E/jU338wA8vM5Ic6okiyjA6h6UjS /sf2UZAhLKmHMyDVEftgpJfeb2LkIqyMS22JBeoKm1ZzmS9uoSh776B7rmQu45Tr1Eyk b6g1ie+tI5xu0EtLAO3cMhHUbB5iNznRN/uPtsvYuv9wYBTQ/Kdlt27slMyS5nEh/DbN EiV6fiejJ3Acp1z/Dmh0Jw3K6ZT3DeJiYlYg96k03C5ixCeRPeuD6ZVS9jglq5amgIsy U/DsYGO9mgVQLRRajEwjmCSNnR+p4kzcs26Nb4+zflSzZAaedSblsjvkvIC642Rj6tra meuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:from:to:cc:references:in-reply-to :content-transfer-encoding; bh=HDKqg2pWAZz4uZmdk0aehi0Cj5oQsrM+ze2oyg6/ka8=; b=BujLR+Wh4GMUv4aIqMNnoARvfYrVrLVVPU0qsf/yWVj/5LKRGtwK5vUB80nUNLPedX 1m78JlvBaL43zdW8igy92uzmBl7rd1j+R5rQ6p92TQ5f+fbYnzI4CmfbywX7LHMoOHzB V7noz38KZ4/4cTMIkkeXluGdVTh19TwU7qQGW9vXibKVEhWka0djBd04YIHA9fcey9UR ydTQWCy2/W+gW6TE3TdvrUVo2SSO8hg9gmRnlA5NjezfmgDV7Gy0rveAXv1X4O0+DQEA qjfy5Ryj6j+uFdqRqwqFwY2OmNuyY4BarQY/eeFqpgBgQDYOLTB4EU3zWQctJey9fbLG JY1A== X-Gm-Message-State: AOAM533SMgpksYSV+jfaMCfOrWQDGOdXKIpR4WttSMU+F5tn8l3Aa39y Ir8p106GQwADcdW2olFLoQI= X-Google-Smtp-Source: ABdhPJxuCgfW7FXJHm3t6ylzMioZ3xPSWUcqhQpUAdyg7/84fDtl/vTFHavcuQ9RFbHfOp/unyATkA== X-Received: by 2002:a2e:7801:: with SMTP id t1mr11675248ljc.192.1630947106476; Mon, 06 Sep 2021 09:51:46 -0700 (PDT) Received: from [192.168.1.11] ([46.235.67.70]) by smtp.gmail.com with UTF8SMTPSA id 23sm782298lfp.47.2021.09.06.09.51.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Sep 2021 09:51:46 -0700 (PDT) Message-ID: <4c183bd4-bb51-4c4e-d097-998b213bef66@gmail.com> Date: Mon, 6 Sep 2021 19:51:43 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0.1 Subject: Re: [PATCH] nilfs2: fix memory leak in nilfs_sysfs_create_device_group Content-Language: en-US From: Pavel Skripkin To: Dongliang Mu , Ryusuke Konishi Cc: linux-nilfs@vger.kernel.org, linux-kernel References: <20210906041330.2065214-1-mudongliangabcd@gmail.com> <53fb4217-21b8-ac46-bb39-581a4c9837a4@gmail.com> In-Reply-To: <53fb4217-21b8-ac46-bb39-581a4c9837a4@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/6/21 19:47, Pavel Skripkin wrote: > On 9/6/21 18:56, Pavel Skripkin wrote: >> On 9/6/21 08:43, Dongliang Mu wrote: >>> On Mon, Sep 6, 2021 at 12:13 PM Dongliang Mu wrote: >>>> >>>> The commit 8fd0c1b0647a ("nilfs2: fix memory leak in >>>> nilfs_sysfs_delete_device_group") adds a kobject_put to free the leaking >>>> object name. However, it is incomplete to only add kobject_put in the >>>> nilfs_sysfs_delete_device_group. The function >>>> nilfs_sysfs_create_device_group also needs the kobject_put to >>>> free the object name in the error handling part. >>>> >>>> Fix this by adding kobject_put in the error handling code of >>>> nilfs_sysfs_create_device_group. >>> >>> Even after I add this patch, my local syzkaller still reports this >>> memory leak one hour later. Therefore, there are some other paths or >>> magics which can trigger the memory leak. I need to dig deeper. >>> >>> Pavel, do you have any idea about this crash report? >>> >>> BUG: memory leak >>> unreferenced object 0xffff88804a1a8a60 (size 32): >>> comm "syz-executor", pid 14551, jiffies 4294960586 (age 14.780s) >>> hex dump (first 32 bytes): >>> 6c 6f 6f 70 35 00 00 00 00 00 00 00 00 00 00 00 loop5........... >>> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >>> backtrace: >>> [] kstrdup+0x36/0x70 >>> [] kstrdup_const+0x53/0x80 >>> [] kvasprintf_const+0xc2/0x110 >>> [] kobject_set_name_vargs+0x3b/0xe0 >>> [] kobject_init_and_add+0x6d/0xc0 >>> [] nilfs_sysfs_create_device_group+0x98/0x3a0 >>> [] init_nilfs+0x424/0x580 >>> [] nilfs_mount+0x532/0x8c0 >>> [] legacy_get_tree+0x2b/0x90 >>> [] vfs_get_tree+0x28/0x100 >>> [] path_mount+0xb92/0xfe0 >>> [] do_mount+0xa1/0xc0 >>> [] __x64_sys_mount+0xf4/0x160 >>> [] do_syscall_64+0x35/0xb0 >>> [] entry_SYSCALL_64_after_hwframe+0x44/0xae >>> >>> >> >> Hi, Dongliang! >> >> >> This report says nothing to me... It shows, that there is missing >> kobject_put() somewhere. I think, we need a reproducer for this leak, >> otherwise only code review can help :( >> >> >> > > Hm, I guess, I see... We should call kobject_put() in case of > kobject_init_and_add() failure: > > lib/kobject.c:459 > > * If this function returns an error, kobject_put() must be called to > * properly clean up the memory associated with the object. This is the > > > so I suggest: > > diff --git a/fs/nilfs2/sysfs.c b/fs/nilfs2/sysfs.c > index 68e8d61e28dd..e8717f4ba2a1 100644 > --- a/fs/nilfs2/sysfs.c > +++ b/fs/nilfs2/sysfs.c > @@ -1026,6 +1026,7 @@ int nilfs_sysfs_create_device_group(struct > super_block *sb) kobject_del(&nilfs->ns_dev_kobj); > > free_dev_subgroups: > + kobject_put(&nilfs->ns_dev_kobj); > kfree(nilfs->ns_dev_subgroups); > > failed_create_device_group: > > > This patch should fix 2 memory leaks :) > > Also, I think, we should add kobject_put() call to 1. nilfs_sysfs_create_##name##_group 2. nilfs_sysfs_create_snapshot_group To prevent other random kobject memory leaks in nilfs... With regards, Pavel Skripkin