Messages in this thread | | | Date | Tue, 16 May 2023 13:31:53 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [PATCH] bpf: reject blacklisted symbols in kprobe_multi to avoid recursive trap |
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On Sat, 13 May 2023 00:17:57 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Fri, 12 May 2023 07:29:02 -0700 > Yonghong Song <yhs@meta.com> wrote: > > > A fprobe_blacklist might make sense indeed as fprobe and kprobe are > > quite different... Thanks for working on this. > > Hmm, I think I see the problem: > > fprobe_kprobe_handler() { > kprobe_busy_begin() { > preempt_disable() { > preempt_count_add() { <-- trace > fprobe_kprobe_handler() { > [ wash, rinse, repeat, CRASH!!! ] > > Either the kprobe_busy_begin() needs to use preempt_disable_notrace() > versions, or fprobe_kprobe_handle() needs a > ftrace_test_recursion_trylock() call.
Oops, I got it. Is preempt_count_add() tracable? If so, kprobe_busy_begin() should be updated.
Thanks,
> > -- Steve
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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