lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <20220624125117.bi5o4ovuhhtgs44x@quack3.lan> Date: Fri, 24 Jun 2022 14:51:17 +0200 From: Jan Kara <jack@...e.cz> To: Zhang Yi <yi.zhang@...wei.com> Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz, yukuai3@...wei.com Subject: Re: [PATCH] ext4: silence the warning when evicting inode with dioread_nolock On Fri 24-06-22 15:04:04, Zhang Yi wrote: > When evicting an inode with default dioread_nolock, it could be raced by > the unwritten extents converting kworker after writeback some new > allocated dirty blocks. It convert unwritten extents to written, the > extents could be merged to upper level and free extent blocks, so it > could mark the inode dirty again even this inode has been marked > I_FREEING. But the inode->i_io_list check and warning in > ext4_evict_inode() missing this corner case. Fortunately, > ext4_evict_inode() will wait all extents converting finished before this > check, so it will not lead to inode use-after-free problem, so every > thing is OK besides this warning, let the WARN_ON_ONCE know the > dioread_nolock case to silence this warning is fine. > > ====== > WARNING: CPU: 7 PID: 1092 at fs/ext4/inode.c:227 > ext4_evict_inode+0x875/0xc60 > ... > RIP: 0010:ext4_evict_inode+0x875/0xc60 > ... > Call Trace: > <TASK> > evict+0x11c/0x2b0 > iput+0x236/0x3a0 > do_unlinkat+0x1b4/0x490 > __x64_sys_unlinkat+0x4c/0xb0 > do_syscall_64+0x3b/0x90 > entry_SYSCALL_64_after_hwframe+0x46/0xb0 > RIP: 0033:0x7fa933c1115b > ====== > > rm kworker > ext4_end_io_end() > vfs_unlink() > ext4_unlink() > ext4_convert_unwritten_io_end_vec() > ext4_convert_unwritten_extents() > ext4_map_blocks() > ext4_ext_map_blocks() > ext4_ext_try_to_merge_up() > __mark_inode_dirty() > check !I_FREEING > locked_inode_to_wb_and_lock_list() > iput() > iput_final() > evict() > ext4_evict_inode() > truncate_inode_pages_final() //wait release io_end > inode_io_list_move_locked() > ext4_release_io_end() > trigger WARN_ON_ONCE() > > Fixes: ceff86fddae8 ("ext4: Avoid freeing inodes on dirty list") > Signed-off-by: Zhang Yi <yi.zhang@...wei.com> Good catch! So for the i_nlink == 0 case below, I'd just remove the WARN_ON_ONCE altogether. It isn't very useful after your change anyway. But probably we should add: WARN_ON_ONCE(!list_empty(&inode->i_io_list)); to the no_delete: case of ext4_evict_inode()? Race like you mention above does not seem possible for that case but seeing the complicated interactions I'd rather have the assertion in place. Honza > --- > fs/ext4/inode.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c > index 3dce7d058985..3b64d72416b7 100644 > --- a/fs/ext4/inode.c > +++ b/fs/ext4/inode.c > @@ -220,11 +220,14 @@ void ext4_evict_inode(struct inode *inode) > > /* > * For inodes with journalled data, transaction commit could have > - * dirtied the inode. Flush worker is ignoring it because of I_FREEING > - * flag but we still need to remove the inode from the writeback lists. > + * dirtied the inode. And for inodes with dioread_nolock, unwritten > + * extents converting worker could merged extents and also have dirtied > + * the inode. Flush worker is ignoring it because of I_FREEING flag but > + * we still need to remove the inode from the writeback lists. > */ > if (!list_empty_careful(&inode->i_io_list)) { > - WARN_ON_ONCE(!ext4_should_journal_data(inode)); > + WARN_ON_ONCE(!ext4_should_journal_data(inode) && > + !ext4_should_dioread_nolock(inode)); > inode_io_list_del(inode); > } > > -- > 2.31.1 > -- Jan Kara <jack@...e.com> SUSE Labs, CR
Powered by blists - more mailing lists