Re: [for-linus][PATCH 2/5] tracing/uprobe: Fix double perf_event linking on multiprobe uprobe

Masami Hiramatsu
2020-01-22T22:12:42Z

On Tue, 21 Jan 2020 16:06:05 +0100
Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, Jan 21, 2020 at 02:59:35PM +0000, David Laight wrote:
> > From: Peter Zijlstra
> > > Sent: 21 January 2020 14:50
> > > On Tue, Jan 21, 2020 at 09:38:49AM -0500, Steven Rostedt wrote:
> > > > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> > > > index 4ee703728aec..03e4e180058d 100644
> > > > --- a/kernel/trace/trace_probe.h
> > > > +++ b/kernel/trace/trace_probe.h
> > > > @@ -230,6 +230,7 @@ struct trace_probe_event {
> > > > struct trace_event_call call;
> > > > struct list_head files;
> > > > struct list_head probes;
> > > > + char data[0];
> > > > };
> > >
> > > Note that this relies on pure 'luck'. If you stick anything <4 bytes in
> > > between the list_head and the data member it'll come unstuck real fast.
> >
> > Can you fix it by adding an unnamed struct as in:
>
> The trivial fix is like I suggested in the other thread:
>
> struct trace_uprobe_filter filters[0];
>
> The alternative that Masami-San suggested should also work.

I've sent a fix ( https://lkml.org/lkml/2020/1/21/1214 )
as Peter suggested, change the field to

struct trace_uprobe_filter filters[0];

and change the code around that.

Thank you,

--
Masami Hiramatsu <mhiramat@kernel.org>