linux-kernel - Re: [PATCH 5/7] ftrace: Store direct called addresses in their ops

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABRcYmL_JCAGSoX98dZUhGkmek+5iL4kd+F_POJ65GfnZLADcg@mail.gmail.com>
Date:   Mon, 20 Mar 2023 18:45:08 +0100
From:   Florent Revest <revest@...omium.org>
To:     Jiri Olsa <olsajiri@...il.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org, mhiramat@...nel.org,
        mark.rutland@....com, ast@...nel.org, daniel@...earbox.net,
        kpsingh@...nel.org
Subject: Re: [PATCH 5/7] ftrace: Store direct called addresses in their ops

On Sun, Mar 19, 2023 at 7:55 PM Jiri Olsa <olsajiri@...il.com> wrote:
>
> On Sun, Mar 19, 2023 at 01:54:43PM -0400, Steven Rostedt wrote:
> > On Sun, 19 Mar 2023 16:29:22 +0100
> > Jiri Olsa <olsajiri@...il.com> wrote:
> >
> > > > +++ b/kernel/trace/ftrace.c
> > > > @@ -2582,9 +2582,8 @@ ftrace_add_rec_direct(unsigned long ip, unsigned long addr,
> > > >  static void call_direct_funcs(unsigned long ip, unsigned long pip,
> > > >                         struct ftrace_ops *ops, struct ftrace_regs *fregs)
> > > >  {
> > > > - unsigned long addr;
> > > > + unsigned long addr = ops->direct_call;
> > >
> > > nice, should it be read with READ_ONCE ?
> >
> > Is there a "read tearing" too?
>
> don't know, saw the comment in __modify_ftrace_direct and got curious
> why it's not in here.. feel free to ignore, I'll look it up
>
> jirka

Mhh, that's a good question. Based on my current understanding, it
seems that it should have a READ_ONCE, indeed. However, I'd like Mark
to confirm/deny this. :)

If this should be a READ_ONCE, I can send a v2 series with this fixed.