From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function
Date: Wed, 31 Jan 2024 01:12:46 +0000 [thread overview]
Message-ID: <20240131011246.GP2087318@ZenIV> (raw)
In-Reply-To: <20240130190355.11486-6-torvalds@linux-foundation.org>
On Tue, Jan 30, 2024 at 11:03:55AM -0800, Linus Torvalds wrote:
> +void eventfs_d_release(struct dentry *dentry)
> {
> - struct eventfs_inode *ei;
> -
> - mutex_lock(&eventfs_mutex);
> - ei = dentry->d_fsdata;
> - if (ei) {
> - dentry->d_fsdata = NULL;
> - put_ei(ei);
> - }
> - mutex_unlock(&eventfs_mutex);
> + put_ei(dentry->d_fsdata);
> }
I'd rather pass ->d_fsdata to that sucker (or exposed put_ei(),
for that matter).
> @@ -857,6 +847,5 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei)
> * sticks around while the other ei->dentry are created
> * and destroyed dynamically.
> */
> - simple_recursive_removal(dentry, NULL);
That also needs to move earlier in the series - bisect hazard.
> + *
> + * Note that d_revalidate is called potentially under RCU,
> + * so it can't take the eventfs mutex etc. It's fine - if
> + * we open a file just as it's marked dead, things will
> + * still work just fine, and just see the old stale case.
Looks like use after free, unless freeing ei is RCU-delayed...
> + return !(ei && ei->is_freed);
next prev parent reply other threads:[~2024-01-31 1:12 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 19:03 [PATCH 1/6] tracefs: avoid using the ei->dentry pointer unnecessarily Linus Torvalds
2024-01-30 19:03 ` [PATCH 2/6] eventfsfs: initialize the tracefs inode properly Linus Torvalds
2024-01-30 19:48 ` Steven Rostedt
2024-01-30 19:56 ` Steven Rostedt
2024-01-30 19:49 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 3/6] tracefs: dentry lookup crapectomy Linus Torvalds
2024-01-30 23:26 ` Al Viro
2024-01-30 23:55 ` Steven Rostedt
2024-01-31 0:07 ` Al Viro
2024-01-31 0:23 ` Al Viro
2024-01-31 0:39 ` Linus Torvalds
2024-01-30 19:03 ` [PATCH 4/6] eventfs: remove unused 'd_parent' pointer field Linus Torvalds
2024-01-30 19:03 ` [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts Linus Torvalds
2024-01-30 20:55 ` Steven Rostedt
2024-01-30 21:52 ` Linus Torvalds
2024-01-30 22:56 ` Steven Rostedt
2024-01-30 22:58 ` Linus Torvalds
2024-01-30 23:04 ` Steven Rostedt
2024-01-30 22:56 ` Linus Torvalds
2024-01-30 23:06 ` Linus Torvalds
2024-01-30 23:10 ` Steven Rostedt
2024-01-30 23:25 ` Linus Torvalds
2024-01-31 0:48 ` Al Viro
2024-01-31 5:09 ` Steven Rostedt
2024-01-31 5:25 ` Linus Torvalds
2024-01-31 5:33 ` Steven Rostedt
2024-01-31 5:57 ` Linus Torvalds
2024-01-31 6:20 ` Linus Torvalds
2024-01-31 12:57 ` Steven Rostedt
2024-01-31 13:14 ` Steven Rostedt
2024-01-31 18:08 ` Linus Torvalds
2024-01-31 18:39 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function Linus Torvalds
2024-01-30 21:25 ` Steven Rostedt
2024-01-30 21:36 ` Linus Torvalds
2024-01-31 1:12 ` Al Viro [this message]
2024-01-31 2:37 ` Linus Torvalds
2024-01-31 2:46 ` Al Viro
2024-01-31 3:39 ` Linus Torvalds
2024-01-31 4:28 ` Al Viro
2024-01-31 18:00 ` Steven Rostedt
2024-01-31 23:07 ` Masami Hiramatsu
2024-01-31 23:23 ` Steven Rostedt
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=20240131011246.GP2087318@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-trace-kernel@vger.kernel.org \
--cc=mhiramat@kernel.org \
--cc=rostedt@goodmis.org \
--cc=torvalds@linux-foundation.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).