From: Al Viro <viro@zeniv.linux.org.uk>
To: Hillf Danton <hdanton@sina.com>
Cc: syzbot <syzbot+d88a977731a9888db7ba@syzkaller.appspotmail.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"syzkaller-bugs@googlegroups.com"
<syzkaller-bugs@googlegroups.com>
Subject: Re: kernel panic: corrupted stack end in dput
Date: Wed, 3 Jul 2019 15:40:00 +0100 [thread overview]
Message-ID: <20190703144000.GH17978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190703064307.13740-1-hdanton@sina.com>
On Wed, Jul 03, 2019 at 02:43:07PM +0800, Hillf Danton wrote:
> > This is very much *NOT* fine.
> > 1) trylock can fail from any number of reasons, starting
> > with "somebody is going through the hash chain doing a lookup on
> > something completely unrelated"
>
> They are also a red light that we need to bail out of spiraling up
> the directory hierarchy imho.
Translation: "let's leak the reference to parent, shall we?"
> > 2) whoever had been holding the lock and whatever they'd
> > been doing might be over right after we get the return value from
> > spin_trylock().
>
> Or after we send a mail using git. I don't know.
>
> > 3) even had that been really somebody adding children in
> > the same parent *AND* even if they really kept doing that, rather
> > than unlocking and buggering off, would you care to explain why
> > dentry_unlist() called by __dentry_kill() and removing the victim
> > from the list of children would be safe to do in parallel with that?
> >
> My bad. I have to walk around that unsafety.
WHAT unsafety? Can you explain what are you seeing and how to
reproduce it, whatever it is?
next parent reply other threads:[~2019-07-03 14:40 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190703064307.13740-1-hdanton@sina.com>
2019-07-03 14:40 ` Al Viro [this message]
2019-07-03 15:23 ` kernel panic: corrupted stack end in dput Al Viro
2019-07-03 15:45 ` Eric Biggers
2019-07-03 16:14 ` John Fastabend
2019-07-01 8:27 syzbot
2019-07-01 12:14 ` syzbot
2019-07-02 13:21 ` Al Viro
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