linux-kernel - Re: [PATCH 1/7 v2] tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down")

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Message-ID: <20191012203502.065258d2@gandalf.local.home>
Date:   Sat, 12 Oct 2019 20:35:02 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Garrett <matthewgarrett@...gle.com>,
        James Morris James Morris <jmorris@...ei.org>,
        LSM List <linux-security-module@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Ben Hutchings <ben@...adent.org.uk>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 1/7 v2] tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict
 tracefs when the kernel is locked down")

On Sat, 12 Oct 2019 15:56:15 -0700
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Fri, Oct 11, 2019 at 5:59 PM Steven Rostedt <rostedt@...dmis.org> wrote:
> >
> >
> > I bisected this down to the addition of the proxy_ops into tracefs for
> > lockdown. It appears that the allocation of the proxy_ops and then freeing
> > it in the destroy_inode callback, is causing havoc with the memory system.
> > Reading the documentation about destroy_inode and talking with Linus about
> > this, this is buggy and wrong.  
> 
> Can you still add the explanation about the inode memory leak to this message?
> 
> Right now it just says "it's buggy and wrong". True. But doesn't
> explain _why_ it is buggy and wrong.
> 

Sure. The patches just finished my testing (along with other fixes that
I need to send you). I have to make a few other updates in the change
log though, so I'll be rebasing them (but not touching the code), to
clean up the change logs.

-- Steve