From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752760AbeCQDB6 (ORCPT ); Fri, 16 Mar 2018 23:01:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:51068 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbeCQDB5 (ORCPT ); Fri, 16 Mar 2018 23:01:57 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13D3621742 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Fri, 16 Mar 2018 23:01:54 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: Mathieu Desnoyers , Francis Deslauriers , Peter Zijlstra , linux-kernel , Linus Torvalds Subject: Re: [PATCH 2/2] kprobe: fix: Add ftrace_ops_assist_func to kprobe blacklist Message-ID: <20180316230154.2d34a98c@vmware.local.home> In-Reply-To: <20180317102211.a648f26ae0d5a53d95c63022@kernel.org> References: <1500044315-9508-1-git-send-email-francis.deslauriers@efficios.com> <1500044315-9508-3-git-send-email-francis.deslauriers@efficios.com> <20170714142900.1c91949c@gandalf.local.home> <20180316112517.66bdd85a@gandalf.local.home> <229385456.11580.1521217739037.JavaMail.zimbra@efficios.com> <20180316124134.30fa47d5@gandalf.local.home> <20180316124840.3e83bbec@gandalf.local.home> <1577244734.11604.1521222781948.JavaMail.zimbra@efficios.com> <20180317091334.55f1fc325c26deaa4d4a4d19@kernel.org> <20180317102211.a648f26ae0d5a53d95c63022@kernel.org> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 17 Mar 2018 10:22:11 +0900 Masami Hiramatsu wrote: > Or, we can check it by ftrace_location_range() as below patch. Cute ;-) > > Note that as a side-effect, we can not trace functions in trace_kprobe.c > anymore, and this means it is hard to me to make a testcase of kprobe events. > It was the easiest (and maintainable) way to make test cases... sigh. > > ----- > tracing: kprobes: Prohibit probing on notrace function > > From: Masami Hiramatsu > > Prohibit kprobe-events probing on notrace function. > Since probing on the notrace function can cause recursive > event call. In most case those are just skipped, but > in some case it falls into infinit recursive call. > > Signed-off-by: Masami Hiramatsu > --- > kernel/trace/trace_kprobe.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 5ce9b8cf7be3..7404b012e51a 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -487,6 +487,23 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) > return ret; > } > > +#ifdef CONFIG_KPROBES_ON_FTRACE > +static bool within_notrace_func(struct trace_kprobe *tk) > +{ > + unsigned long offset, size, addr; > + > + addr = kallsyms_lookup_name(trace_kprobe_symbol(tk)); > + addr += trace_kprobe_offset(tk); > + > + if (!kallsyms_lookup_size_offset(addr, &size, &offset)) > + return true; /* Out of range. */ > + > + return !ftrace_location_range(addr - offset, addr - offset + size); > +} > +#else > +#define within_notrace_func(tk) (false) > +#endif > + > /* Internal register function - just handle k*probes and flags */ > static int __register_trace_kprobe(struct trace_kprobe *tk) > { > @@ -495,6 +512,12 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) > if (trace_probe_is_registered(&tk->tp)) > return -EINVAL; > > + if (within_notrace_func(tk)) { > + pr_warn("Could not probe notrace function %s\n", > + trace_kprobe_symbol(tk)); > + return -EINVAL; > + } This will prevent probing assembly code. Do we want to do that? Or is kprobes already prohibited from doing so? -- Steve > + > for (i = 0; i < tk->tp.nr_args; i++) > traceprobe_update_arg(&tk->tp.args[i]); > >