From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966695AbcDLXb1 (ORCPT ); Tue, 12 Apr 2016 19:31:27 -0400 Received: from mail.kernel.org ([198.145.29.136]:57332 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964879AbcDLXb0 (ORCPT ); Tue, 12 Apr 2016 19:31:26 -0400 Date: Tue, 12 Apr 2016 16:31:23 -0700 From: Jaegeuk Kim To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, "Theodore Ts'o" Subject: Re: [PATCH 1/3] fscrypto: use dget_parent() in fscrypt_d_revalidate() Message-ID: <20160412233123.GA17607@jaegeuk.gateway> References: <1460482042-14011-1-git-send-email-jaegeuk@kernel.org> <20160412223303.GQ25498@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160412223303.GQ25498@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 12, 2016 at 11:33:03PM +0100, Al Viro wrote: > On Tue, Apr 12, 2016 at 10:27:20AM -0700, Jaegeuk Kim wrote: > > This patch updates fscrypto along with the below ext4 crypto change. > > > > Fixes: 3d43bcfef5f0 ("ext4 crypto: use dget_parent() in ext4_d_revalidate()") > > > static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) > > { > > - struct inode *dir = d_inode(dentry->d_parent); > > - struct fscrypt_info *ci = dir->i_crypt_info; > > + struct dentry *dir; > > + struct fscrypt_info *ci; > > int dir_has_key, cached_with_key; > > > > - if (!dir->i_sb->s_cop->is_encrypted(dir)) > > + dir = dget_parent(dentry); > > + if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) { > > + dput(dir); > > ... and as soon as you call it from RCU mode, you are screwed. Thank you for pointing this out. IIUC, did you mean this? Thanks, >>From a0ac7972189b7c366720a0b456e39516d622a6d4 Mon Sep 17 00:00:00 2001 From: Jaegeuk Kim Date: Tue, 12 Apr 2016 16:05:36 -0700 Subject: [PATCH] ext4/fscrypto: avoid RCU lookup in d_revalidate As Al pointed, d_revalidate should return RCU lookup before using d_inode. This was originally introduced by: commit 34286d666230 ("fs: rcu-walk aware d_revalidate method"). Reported-by: Al Viro Signed-off-by: Jaegeuk Kim Cc: Theodore Ts'o Cc: stable --- fs/crypto/crypto.c | 4 ++++ fs/ext4/crypto.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c index da70520..2fc8c43 100644 --- a/fs/crypto/crypto.c +++ b/fs/crypto/crypto.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -353,6 +354,9 @@ static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) struct fscrypt_info *ci; int dir_has_key, cached_with_key; + if (flags & LOOKUP_RCU) + return -ECHILD; + dir = dget_parent(dentry); if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) { dput(dir); diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c index db9ae6e..6a6c273 100644 --- a/fs/ext4/crypto.c +++ b/fs/ext4/crypto.c @@ -32,6 +32,7 @@ #include #include #include +#include #include "ext4_extents.h" #include "xattr.h" @@ -482,6 +483,9 @@ static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags) struct ext4_crypt_info *ci; int dir_has_key, cached_with_key; + if (flags & LOOKUP_RCU) + return -ECHILD; + dir = dget_parent(dentry); if (!ext4_encrypted_inode(d_inode(dir))) { dput(dir); -- 2.6.3