Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934160AbcCQJBe (ORCPT ); Thu, 17 Mar 2016 05:01:34 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:33972 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932821AbcCQJA6 (ORCPT ); Thu, 17 Mar 2016 05:00:58 -0400 From: Miklos Szeredi To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: dhowells@redhat.com, viro@zeniv.linux.org.uk, "Theodore Ts'o" , Subject: [PATCH 3/4] ext4: use dget_parent() in ext4_file_open() Date: Thu, 17 Mar 2016 10:02:02 +0100 Message-Id: <1458205323-25685-3-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1458205323-25685-1-git-send-email-miklos@szeredi.hu> References: <1458205323-25685-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1874 Lines: 53 From: Miklos Szeredi In f_op->open() lock on parent is not held, so there's no guarantee that parent dentry won't go away at any time. Even after this patch there's no guarantee that 'dir' will stay the parent of 'inode', but at least it won't be freed while being used. Fixes: ff978b09f973 ("ext4 crypto: move context consistency check to ext4_file_open()") Signed-off-by: Miklos Szeredi Cc: Theodore Ts'o Cc: # v4.5 --- fs/ext4/file.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 4cd318f31cbe..feb9ffc6f20d 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -335,7 +335,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp) struct super_block *sb = inode->i_sb; struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); struct vfsmount *mnt = filp->f_path.mnt; - struct inode *dir = filp->f_path.dentry->d_parent->d_inode; + struct dentry *dir; struct path path; char buf[64], *cp; int ret; @@ -379,14 +379,18 @@ static int ext4_file_open(struct inode * inode, struct file * filp) if (ext4_encryption_info(inode) == NULL) return -ENOKEY; } - if (ext4_encrypted_inode(dir) && - !ext4_is_child_context_consistent_with_parent(dir, inode)) { + + dir = dget_parent(filp->f_path.dentry); + if (ext4_encrypted_inode(d_inode(dir)) && + !ext4_is_child_context_consistent_with_parent(d_inode(dir), inode)) { ext4_warning(inode->i_sb, "Inconsistent encryption contexts: %lu/%lu\n", - (unsigned long) dir->i_ino, + (unsigned long) d_inode(dir)->i_ino, (unsigned long) inode->i_ino); + dput(dir); return -EPERM; } + dput(dir); /* * Set up the jbd2_inode if we are opening the inode for * writing and the journal is present -- 2.1.4