Messages in this thread | | | Date | Fri, 16 Mar 2018 23:01:54 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 2/2] kprobe: fix: Add ftrace_ops_assist_func to kprobe blacklist |
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On Sat, 17 Mar 2018 10:22:11 +0900 Masami Hiramatsu <mhiramat@kernel.org> 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 <mhiramat@kernel.org> > > 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 <mhiramat@kernel.org> > --- > 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]); > >
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