linux-kernel - Re: [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order problem

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Message-ID: <20190107142749.34231bb6@gandalf.local.home>
Date:   Mon, 7 Jan 2019 14:27:49 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Andrea Righi <righi.andrea@...il.com>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Ingo Molnar <mingo@...hat.com>, peterz@...radead.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order
 problem

On Mon, 7 Jan 2019 19:34:44 +0100
Andrea Righi <righi.andrea@...il.com> wrote:

> On Mon, Jan 07, 2019 at 10:31:34PM +0900, Masami Hiramatsu wrote:
> ...
> > BTW, this is not all of issues. To remove CONFIG_KPROBE_EVENTS_ON_NOTRACE
> > I'm trying to find out other notrace functions which can cause
> > kernel crash by probing. Mostly done on x86, so I'll post it
> > after this series.  
> 
> Not sure if you found it already, but it looks like some of the
> _raw_spin_lock/unlock* functions (when they're not inlined) are causing
> the same problem (or something similar), I can deadlock the system by
> doing this for example:
> 
>  echo "r:event_1 __fdget" >> kprobe_events
>  echo "r:event_2 _raw_spin_lock_irqsave" >> kprobe_events
>  echo 1 > events/kprobes/enable
>  [DEADLOCK]
> 
> Sending the following just in case...
>

Ug, kretprobe calls spinlocks in the callback? I wonder if we can
remove them.

I'm guessing this is a different issue than the one that this patch
fixes. This sounds like we are calling kretprobe from kretprobe?

-- Steve