From patchwork Wed Oct 13 04:01:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: ChenXiaoSong X-Patchwork-Id: 12554443 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF343C433EF for ; Wed, 13 Oct 2021 03:53:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B438A60F11 for ; Wed, 13 Oct 2021 03:53:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237160AbhJMDzQ (ORCPT ); Tue, 12 Oct 2021 23:55:16 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:28923 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229717AbhJMDzP (ORCPT ); Tue, 12 Oct 2021 23:55:15 -0400 Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.57]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4HTdmq3YwSzbn59; Wed, 13 Oct 2021 11:48:43 +0800 (CST) Received: from kwepemm600015.china.huawei.com (7.193.23.52) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Wed, 13 Oct 2021 11:53:11 +0800 Received: from huawei.com (10.175.101.6) by kwepemm600015.china.huawei.com (7.193.23.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Wed, 13 Oct 2021 11:53:09 +0800 From: ChenXiaoSong To: , , CC: , , , , , Subject: [PATCH linux-4.19.y] VFS: Fix fuseblk memory leak caused by mount concurrency Date: Wed, 13 Oct 2021 12:01:32 +0800 Message-ID: <20211013040132.502406-1-chenxiaosong2@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600015.china.huawei.com (7.193.23.52) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org If two processes mount same superblock, memory leak occurs: CPU0 | CPU1 do_new_mount | do_new_mount fs_set_subtype | fs_set_subtype kstrdup | | kstrdup memrory leak | Fix this by moving fs_set_subtype to mount_fs before up_write(&sb->s_umount). Linus's tree already have refactoring patchset [1], one of them can fix this bug: c30da2e981a7 (fuse: convert to use the new mount API) Since we did not merge the refactoring patchset in this branch, I create this patch. [1] https://patchwork.kernel.org/project/linux-fsdevel/patch/20190903113640.7984-3-mszeredi@redhat.com/ Fixes: 9d412a43c3b2 (vfs: split off vfsmount-related parts of vfs_kern_mount()) Cc: David Howells Signed-off-by: ChenXiaoSong --- fs/namespace.c | 26 -------------------------- fs/super.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+), 26 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 2f3c6a0350a8..556fdd3b6a4e 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2402,29 +2402,6 @@ static int do_move_mount(struct path *path, const char *old_name) return err; } -static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) -{ - int err; - const char *subtype = strchr(fstype, '.'); - if (subtype) { - subtype++; - err = -EINVAL; - if (!subtype[0]) - goto err; - } else - subtype = ""; - - mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); - err = -ENOMEM; - if (!mnt->mnt_sb->s_subtype) - goto err; - return mnt; - - err: - mntput(mnt); - return ERR_PTR(err); -} - /* * add a mount into a namespace's mount tree */ @@ -2490,9 +2467,6 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags, return -ENODEV; mnt = vfs_kern_mount(type, sb_flags, name, data); - if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && - !mnt->mnt_sb->s_subtype) - mnt = fs_set_subtype(mnt, fstype); put_filesystem(type); if (IS_ERR(mnt)) diff --git a/fs/super.c b/fs/super.c index 9fb4553c46e6..b181878753bb 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1240,6 +1240,30 @@ struct dentry *mount_single(struct file_system_type *fs_type, } EXPORT_SYMBOL(mount_single); +static int fs_set_subtype(struct super_block *sb) +{ + int err; + const char *fstype = sb->s_type->name; + const char *subtype = strchr(fstype, '.'); + if (subtype) { + subtype++; + err = -EINVAL; + if (!subtype[0]) + goto err; + } else { + subtype = ""; + } + + sb->s_subtype = kstrdup(subtype, GFP_KERNEL); + err = -ENOMEM; + if (!sb->s_subtype) + goto err; + return 0; + +err: + return err; +} + struct dentry * mount_fs(struct file_system_type *type, int flags, const char *name, void *data) { @@ -1289,6 +1313,12 @@ mount_fs(struct file_system_type *type, int flags, const char *name, void *data) WARN((sb->s_maxbytes < 0), "%s set sb->s_maxbytes to " "negative value (%lld)\n", type->name, sb->s_maxbytes); + if ((sb->s_type->fs_flags & FS_HAS_SUBTYPE) && !sb->s_subtype) { + error = fs_set_subtype(sb); + if (error) + goto out_sb; + } + up_write(&sb->s_umount); free_secdata(secdata); return root;