linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Luis Chamberlain <mcgrof@kernel.org>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Ming Lei <ming.lei@redhat.com>,
	axboe@kernel.dk, viro@zeniv.linux.org.uk,
	gregkh@linuxfoundation.org, rostedt@goodmis.org,
	mingo@redhat.com, jack@suse.cz, nstange@suse.de, mhocko@suse.com,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/3] block: address blktrace use-after-free
Date: Tue, 7 Apr 2020 19:00:04 +0000	[thread overview]
Message-ID: <20200407190004.GG11244@42.do-not-panic.com> (raw)
In-Reply-To: <0e753195-72fb-ce83-16a1-176f2c3cea6a@huawei.com>

On Tue, Apr 07, 2020 at 10:47:01AM +0800, yukuai (C) wrote:
> On 2020/4/3 16:19, Ming Lei wrote:
> 
> > BTW, Yu Kuai posted one patch for this issue, looks that approach
> > is simpler:
> > 
> > https://lore.kernel.org/linux-block/20200324132315.22133-1-yukuai3@huawei.com/
> > 
> > 
> 
> I think the issue might not be fixed with the patch seires.
> 
> At first, I think there are two key points for the issure:
> 1. The final release of queue is delayed in a workqueue
> 2. The creation of 'q->debugfs_dir' might failed(only if 1 exist)
> And if we can fix any of the above problem, the UAF issue will be fixed.
> (BTW, I did not come up with a good idea for problem 1, and my approach
> is for problem 2.)
> 
> The third patch "block: avoid deferral of blk_release_queue() work" is
> not enough to fix problem 1:
> a. if CONFIG_DEBUG_KOBJECT_RELEASE is enable:
> static void kobject_release(struct kref *kref)
> {
>         struct kobject *kobj = container_of(kref, struct kobject, kref);
> #ifdef CONFIG_DEBUG_KOBJECT_RELEASE
>         unsigned long delay = HZ + HZ * (get_random_int() & 0x3);
>         pr_info("kobject: '%s' (%p): %s, parent %p (delayed %ld)\n",
>                 ┊kobject_name(kobj), kobj, __func__, kobj->parent, delay);
>         INIT_DELAYED_WORK(&kobj->release, kobject_delayed_cleanup);
> 
>         schedule_delayed_work(&kobj->release, delay);
> #else
>         kobject_cleanup(kobj);
> #endif
> }
> b. when 'kobject_put' is called from blk_cleanup_queue, can we make sure
> it is the last reference?

You are right, I think I know the fix for this now. Will run some more
tests.

  Luis

  reply	other threads:[~2020-04-07 19:00 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-01 23:59 Luis Chamberlain
2020-04-02  0:00 ` [RFC 1/3] block: move main block debugfs initialization to its own file Luis Chamberlain
2020-04-05  3:12   ` Bart Van Assche
2020-04-06 14:23     ` Luis Chamberlain
2020-04-02  0:00 ` [RFC 2/3] blktrace: fix debugfs use after free Luis Chamberlain
2020-04-02  1:57   ` Eric Sandeen
2020-04-02 16:14     ` Luis Chamberlain
2020-04-05  3:39   ` Bart Van Assche
2020-04-06  1:27     ` Eric Sandeen
2020-04-06  4:25       ` Bart Van Assche
2020-04-06  9:18         ` Nicolai Stange
2020-04-06 15:19           ` Luis Chamberlain
2020-04-07  8:15             ` Luis Chamberlain
2020-04-06 14:29         ` Eric Sandeen
2020-04-07  8:09           ` Luis Chamberlain
2020-04-06 15:14     ` Luis Chamberlain
2020-04-02  0:00 ` [RFC 3/3] block: avoid deferral of blk_release_queue() work Luis Chamberlain
2020-04-02  3:39   ` Bart Van Assche
2020-04-02 14:49     ` Nicolai Stange
2020-04-06  9:11       ` Nicolai Stange
2020-04-09 18:11       ` Luis Chamberlain
2020-04-02  7:44 ` [RFC 0/3] block: address blktrace use-after-free Greg KH
2020-04-03  8:19 ` Ming Lei
2020-04-03 14:06   ` Luis Chamberlain
2020-04-03 14:13   ` Bart Van Assche
2020-04-03 19:49     ` Luis Chamberlain
2020-04-07  2:47   ` yukuai (C)
2020-04-07 19:00     ` Luis Chamberlain [this message]
2020-04-09 20:59       ` Luis Chamberlain

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=20200407190004.GG11244@42.do-not-panic.com \
    --to=mcgrof@kernel.org \
    --cc=axboe@kernel.dk \
    --cc=gregkh@linuxfoundation.org \
    --cc=jack@suse.cz \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhocko@suse.com \
    --cc=ming.lei@redhat.com \
    --cc=mingo@redhat.com \
    --cc=nstange@suse.de \
    --cc=rostedt@goodmis.org \
    --cc=viro@zeniv.linux.org.uk \
    --cc=yukuai3@huawei.com \
    --subject='Re: [RFC 0/3] block: address blktrace use-after-free' \
    /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

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox