From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changman Lee Subject: Re: [PATCH] f2fs: reposition unlock_new_inode to prevent accessing invalid inode Date: Thu, 28 Aug 2014 10:47:36 +0900 Message-ID: <20140828014736.GA6808@lcm> References: <009101cfc119$8e7a5a00$ab6f0e00$@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1XMopn-0000l4-7p for linux-f2fs-devel@lists.sourceforge.net; Thu, 28 Aug 2014 01:49:07 +0000 Received: from mailout2.samsung.com ([203.254.224.25]) by sog-mx-4.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-MD5:128) (Exim 4.76) id 1XMopk-0003ar-V3 for linux-f2fs-devel@lists.sourceforge.net; Thu, 28 Aug 2014 01:49:07 +0000 Received: from epcpsbgr4.samsung.com (u144.gpu120.samsung.co.kr [203.254.230.144]) by mailout2.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NAZ00JQ7UDLN4B0@mailout2.samsung.com> for linux-f2fs-devel@lists.sourceforge.net; Thu, 28 Aug 2014 10:48:57 +0900 (KST) Content-disposition: inline In-reply-to: <009101cfc119$8e7a5a00$ab6f0e00$@samsung.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Chao Yu Cc: Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Hi Chao, I agree it's correct unlock_new_inode should be located after make_bad_inode. About this scenario, I think we should check some condition if this could be occured; A inode allocated newly could be victim by gc thread. Then, f2fs_iget called by Thread A have to fail because we handled it as bad_inode in Thread B. However, f2fs_iget could still get inode. How about check it using is_bad_inode() in f2fs_iget. Thanks, On Tue, Aug 26, 2014 at 06:35:29PM +0800, Chao Yu wrote: > As the race condition on the inode cache, following scenario can appear: > [Thread a] [Thread b] > ->f2fs_mkdir > ->f2fs_add_link > ->__f2fs_add_link > ->init_inode_metadata failed here > ->gc_thread_func > ->f2fs_gc > ->do_garbage_collect > ->gc_data_segment > ->f2fs_iget > ->iget_locked > ->wait_on_inode > ->unlock_new_inode > ->move_data_page > ->make_bad_inode > ->iput > > When we fail in create/symlink/mkdir/mknod/tmpfile, the new allocated inode > should be set as bad to avoid being accessed by other thread. But in above > scenario, it allows f2fs to access the invalid inode before this inode was set > as bad. > This patch fix the potential problem, and this issue was found by code review. > > Signed-off-by: Chao Yu > --- > fs/f2fs/namei.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c > index 6b53ce9..845f1be 100644 > --- a/fs/f2fs/namei.c > +++ b/fs/f2fs/namei.c > @@ -134,8 +134,8 @@ static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode, > return 0; > out: > clear_nlink(inode); > - unlock_new_inode(inode); > make_bad_inode(inode); > + unlock_new_inode(inode); > iput(inode); > alloc_nid_failed(sbi, ino); > return err; > @@ -267,8 +267,8 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry, > return err; > out: > clear_nlink(inode); > - unlock_new_inode(inode); > make_bad_inode(inode); > + unlock_new_inode(inode); > iput(inode); > alloc_nid_failed(sbi, inode->i_ino); > return err; > @@ -308,8 +308,8 @@ static int f2fs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) > out_fail: > clear_inode_flag(F2FS_I(inode), FI_INC_LINK); > clear_nlink(inode); > - unlock_new_inode(inode); > make_bad_inode(inode); > + unlock_new_inode(inode); > iput(inode); > alloc_nid_failed(sbi, inode->i_ino); > return err; > @@ -354,8 +354,8 @@ static int f2fs_mknod(struct inode *dir, struct dentry *dentry, > return 0; > out: > clear_nlink(inode); > - unlock_new_inode(inode); > make_bad_inode(inode); > + unlock_new_inode(inode); > iput(inode); > alloc_nid_failed(sbi, inode->i_ino); > return err; > @@ -688,8 +688,8 @@ release_out: > out: > f2fs_unlock_op(sbi); > clear_nlink(inode); > - unlock_new_inode(inode); > make_bad_inode(inode); > + unlock_new_inode(inode); > iput(inode); > alloc_nid_failed(sbi, inode->i_ino); > return err; > -- > 2.0.0.421.g786a89d > > > > ------------------------------------------------------------------------------ > Slashdot TV. > Video for Nerds. Stuff that matters. > http://tv.slashdot.org/ > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/