From patchwork Mon Jan 8 02:41:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhihao Cheng X-Patchwork-Id: 13512995 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BA68E79D8 for ; Mon, 8 Jan 2024 02:44:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4T7dfn1f62z1wrq4; Mon, 8 Jan 2024 10:43:45 +0800 (CST) Received: from kwepemm600013.china.huawei.com (unknown [7.193.23.68]) by mail.maildlp.com (Postfix) with ESMTPS id 05C421404FD; Mon, 8 Jan 2024 10:44:20 +0800 (CST) Received: from huawei.com (10.175.104.67) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Mon, 8 Jan 2024 10:44:19 +0800 From: Zhihao Cheng To: , , CC: , Subject: [PATCH v3 2/2] ubifs: ubifs_symlink: Fix memleak of inode->i_link in error path Date: Mon, 8 Jan 2024 10:41:05 +0800 Message-ID: <20240108024105.194516-3-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240108024105.194516-1-chengzhihao1@huawei.com> References: <20240108024105.194516-1-chengzhihao1@huawei.com> Precedence: bulk X-Mailing-List: linux-fscrypt@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600013.china.huawei.com (7.193.23.68) For error handling path in ubifs_symlink(), inode will be marked as bad first, then iput() is invoked. If inode->i_link is initialized by fscrypt_encrypt_symlink() in encryption scenario, inode->i_link won't be freed by callchain ubifs_free_inode -> fscrypt_free_inode in error handling path, because make_bad_inode() has changed 'inode->i_mode' as 'S_IFREG'. Following kmemleak is easy to be reproduced by injecting error in ubifs_jnl_update() when doing symlink in encryption scenario: unreferenced object 0xffff888103da3d98 (size 8): comm "ln", pid 1692, jiffies 4294914701 (age 12.045s) backtrace: kmemdup+0x32/0x70 __fscrypt_encrypt_symlink+0xed/0x1c0 ubifs_symlink+0x210/0x300 [ubifs] vfs_symlink+0x216/0x360 do_symlinkat+0x11a/0x190 do_syscall_64+0x3b/0xe0 There are two ways fixing it: 1. Remove make_bad_inode() in error handling path. We can do that because ubifs_evict_inode() will do same processes for good symlink inode and bad symlink inode, for inode->i_nlink checking is before is_bad_inode(). 2. Free inode->i_link before marking inode bad. Method 2 is picked, it has less influence, personally, I think. Cc: stable@vger.kernel.org Fixes: 2c58d548f570 ("fscrypt: cache decrypted symlink target in ->i_link") Signed-off-by: Zhihao Cheng Suggested-by: Eric Biggers Reviewed-by: Eric Biggers --- fs/ubifs/dir.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 3b13c648d490..e413a9cf8ee3 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -1234,6 +1234,8 @@ static int ubifs_symlink(struct mnt_idmap *idmap, struct inode *dir, dir_ui->ui_size = dir->i_size; mutex_unlock(&dir_ui->ui_mutex); out_inode: + /* Free inode->i_link before inode is marked as bad. */ + fscrypt_free_inode(inode); make_bad_inode(inode); iput(inode); out_fname: