From patchwork Fri Mar 5 12:05:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Yi X-Patchwork-Id: 1447786 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-ext4-owner@vger.kernel.org; receiver=) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4DsR95100Sz9sR4 for ; Fri, 5 Mar 2021 22:59:05 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229582AbhCEL6c (ORCPT ); Fri, 5 Mar 2021 06:58:32 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13475 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229528AbhCEL60 (ORCPT ); Fri, 5 Mar 2021 06:58:26 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DsR6241fLzjWpT; Fri, 5 Mar 2021 19:56:26 +0800 (CST) Received: from huawei.com (10.175.127.227) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.498.0; Fri, 5 Mar 2021 19:58:02 +0800 From: "zhangyi (F)" To: CC: , , Subject: [PATCH] ext4: do not try to set xattr into ea_inode if value is empty Date: Fri, 5 Mar 2021 20:05:08 +0800 Message-ID: <20210305120508.298465-1-yi.zhang@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org Syzbot report a warning that ext4 may create an empty ea_inode if set an empty extent attribute to a file on the file system which is no free blocks left. WARNING: CPU: 6 PID: 10667 at fs/ext4/xattr.c:1640 ext4_xattr_set_entry+0x10f8/0x1114 fs/ext4/xattr.c:1640 ... Call trace: ext4_xattr_set_entry+0x10f8/0x1114 fs/ext4/xattr.c:1640 ext4_xattr_block_set+0x1d0/0x1b1c fs/ext4/xattr.c:1942 ext4_xattr_set_handle+0x8a0/0xf1c fs/ext4/xattr.c:2390 ext4_xattr_set+0x120/0x1f0 fs/ext4/xattr.c:2491 ext4_xattr_trusted_set+0x48/0x5c fs/ext4/xattr_trusted.c:37 __vfs_setxattr+0x208/0x23c fs/xattr.c:177 ... Now, ext4 try to store extent attribute into an external inode if ext4_xattr_block_set() return -ENOSPC, but for the case of store an empty extent attribute, store the extent entry into the extent attribute block is enough. A simple reproduce below. fallocate test.img -l 1M mkfs.ext4 -F -b 2048 -O ea_inode test.img mount test.img /mnt dd if=/dev/zero of=/mnt/foo bs=2048 count=500 setfattr -n "user.test" /mnt/foo Reported-by: syzbot+98b881fdd8ebf45ab4ae@syzkaller.appspotmail.com Signed-off-by: zhangyi (F) --- fs/ext4/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 372208500f4e..6aef74f7c9ee 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -2400,7 +2400,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index, * external inode if possible. */ if (ext4_has_feature_ea_inode(inode->i_sb) && - !i.in_inode) { + i.value_len && !i.in_inode) { i.in_inode = 1; goto retry_inode; }