From: Al Viro <viro@zeniv.linux.org.uk>
To: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
Christoph Hellwig <hch@lst.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Namjae Jeon <linkinjeon@kernel.org>,
David Sterba <dsterba@suse.com>,
David Howells <dhowells@redhat.com>,
Miklos Szeredi <miklos@szeredi.hu>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Bob Peterson <rpeterso@redhat.com>,
Steve French <sfrench@samba.org>,
Luis Chamberlain <mcgrof@kernel.org>
Subject: Re: [PATCH 15/15] overlayfs: make use of ->layers safe in rcu pathwalk
Date: Tue, 3 Oct 2023 21:47:49 +0100 [thread overview]
Message-ID: <20231003204749.GA800259@ZenIV> (raw)
In-Reply-To: <CAOQ4uxgPrfsJc6g6W4Q2b-SRSvNpih7NHrV4vybQzrWFa_4rOA@mail.gmail.com>
On Mon, Oct 02, 2023 at 11:53:23AM +0300, Amir Goldstein wrote:
> I've also considered just allocating the extra space for
> ofs->mounts[] at super creation time rather than on super destruction.
> I just cannot get myself to be bothered with this cleanup code
> because of saving memory of ovl_fs.
>
> However, looking closer, we have a wasfull layer->name pointer,
> which is only ever used for ovl_show_options() (to print the original
> requested layer path from mount options).
>
> So I am inclined to move these rarely accessed pointers to
> ofs->layer_names[], which can be used for the temp array for
> kern_unmount_array() because freeing name does not need
> RCU delay AFAICT (?).
AFAICS, it doesn't. The only user after the setup is done is
->show_options(), i.e. show_vfsmnt() and show_mountinfo().
Anyone who tries to use those without making sure that
struct mount is not going to come apart under them will
have far worse troubles...
FWIW, I'm perfectly fine with having these fixes go through your tree;
they are independent from the rest of the series.
next prev parent reply other threads:[~2023-10-03 20:47 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-02 2:28 [RFC][PATCHES] fixes in methods exposed to rcu pathwalk Al Viro
2023-10-02 2:28 ` Al Viro
2023-10-02 2:29 ` [PATCH 01/15] rcu pathwalk: prevent bogus hard errors from may_lookup() Al Viro
2023-10-02 2:30 ` [PATCH 02/15] exfat: move freeing sbi, upcase table and dropping nls into rcu-delayed helper Al Viro
2023-10-02 16:10 ` Linus Torvalds
2023-10-02 18:04 ` Al Viro
2023-10-02 2:30 ` [PATCH 03/15] affs: free affs_sb_info with kfree_rcu() Al Viro
2023-10-02 2:31 ` [PATCH 04/15] hfsplus: switch to rcu-delayed unloading of nls and freeing ->s_fs_info Al Viro
2023-10-02 6:49 ` Christoph Hellwig
2023-10-02 7:14 ` Al Viro
2023-10-02 7:21 ` Al Viro
2023-10-02 18:09 ` Al Viro
2023-10-04 19:04 ` Linus Torvalds
2023-10-04 19:06 ` Linus Torvalds
2023-10-02 2:31 ` [PATCH 05/15] cifs_get_link(): bail out in unsafe case Al Viro
2023-10-02 2:32 ` [PATCH 06/15] procfs: move dropping pde and pid from ->evict_inode() to ->free_inode() Al Viro
2023-10-02 2:33 ` [PATCH 07/15] procfs: make freeing proc_fs_info rcu-delayed Al Viro
2023-10-02 2:33 ` [PATCH 08/15] gfs2: fix an oops in gfs2_permission() Al Viro
2023-10-02 11:46 ` Bob Peterson
2023-10-02 12:59 ` Al Viro
2023-10-02 14:16 ` Al Viro
2023-10-03 14:46 ` Andreas Grünbacher
2023-10-02 2:34 ` [PATCH 09/15] nfs: make nfs_set_verifier() safe for use in RCU pathwalk Al Viro
2023-10-02 2:34 ` [PATCH 10/15] nfs: fix UAF on pathwalk running into umount Al Viro
2023-10-02 2:35 ` [PATCH 11/15] fuse: fix UAF in rcu pathwalks Al Viro
2023-10-02 2:35 ` [PATCH 12/15] afs: fix __afs_break_callback() / afs_drop_open_mmap() race Al Viro
2023-10-02 2:36 ` [PATCH 13/15] overlayfs: move freeing ovl_entry past rcu delay Al Viro
2023-10-02 2:36 ` [PATCH 14/15] ovl_dentry_revalidate_common(): fetch inode once Al Viro
2023-10-02 2:37 ` [PATCH 15/15] overlayfs: make use of ->layers safe in rcu pathwalk Al Viro
2023-10-02 6:40 ` Amir Goldstein
2023-10-02 7:23 ` Al Viro
2023-10-02 8:53 ` Amir Goldstein
2023-10-03 20:47 ` Al Viro [this message]
2023-10-02 5:47 ` [PATCH 14/15] ovl_dentry_revalidate_common(): fetch inode once Amir Goldstein
2023-10-02 5:56 ` Amir Goldstein
2023-10-02 14:47 ` Amir Goldstein
2023-10-02 5:51 ` [PATCH 13/15] overlayfs: move freeing ovl_entry past rcu delay Amir Goldstein
2023-10-02 2:52 ` [RFC][PATCHES] fixes in methods exposed to rcu pathwalk Al Viro
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231003204749.GA800259@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=amir73il@gmail.com \
--cc=brauner@kernel.org \
--cc=dhowells@redhat.com \
--cc=dsterba@suse.com \
--cc=hch@lst.de \
--cc=linkinjeon@kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=mcgrof@kernel.org \
--cc=miklos@szeredi.hu \
--cc=rpeterso@redhat.com \
--cc=sfrench@samba.org \
--cc=torvalds@linux-foundation.org \
--cc=trond.myklebust@hammerspace.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.