Messages in this thread | | | From | Muchun Song <> | Date | Sat, 22 Aug 2020 10:31:36 +0800 | Subject | Re: [External] Re: [PATCH] kprobes: Fix kill kprobe which has been marked as gone |
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On Fri, Aug 21, 2020 at 9:28 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > On Fri, 21 Aug 2020 21:28:43 +0900 > Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > Hi Muchun, > > > > On Thu, 20 Aug 2020 11:19:33 +0800 > > Muchun Song <songmuchun@bytedance.com> wrote: > > > > > If a kprobe is marked as gone, we should not kill it again. Otherwise, > > > we can disarm the kprobe more than once. In that case, the statistics > > > of kprobe_ftrace_enabled can unbalance which can lead to that kprobe > > > do not work. > > > > > > > Good catch! Hmm, I think we also need an assertion in > > kill_kprobe() so that p is already gone. Anyway, this looks good to me. > > > > Acked-by: Masami Hiramatsu <mhiramat@kernel.org> > > > > Thanks! > > > > > Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler") > > BTW, this fixes older bug than this commit. > > Fixes: e8386a0cb22f ("kprobes: support probing module __exit function")
Yeah, it's right. Thanks.
> > Thank you, > > > > Signed-off-by: Muchun Song <songmuchun@bytedance.com> > > > Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com> > > > Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> > > > --- > > > kernel/kprobes.c | 6 +++++- > > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > > index d36e2b017588..7bac3ea44ff4 100644 > > > --- a/kernel/kprobes.c > > > +++ b/kernel/kprobes.c > > > @@ -2422,7 +2422,10 @@ static int kprobes_module_callback(struct notifier_block *nb, > > > mutex_lock(&kprobe_mutex); > > > for (i = 0; i < KPROBE_TABLE_SIZE; i++) { > > > head = &kprobe_table[i]; > > > - hlist_for_each_entry(p, head, hlist) > > > + hlist_for_each_entry(p, head, hlist) { > > > + if (kprobe_gone(p)) > > > + continue; > > > + > > > if (within_module_init((unsigned long)p->addr, mod) || > > > (checkcore && > > > within_module_core((unsigned long)p->addr, mod))) { > > > @@ -2439,6 +2442,7 @@ static int kprobes_module_callback(struct notifier_block *nb, > > > */ > > > kill_kprobe(p); > > > } > > > + } > > > } > > > if (val == MODULE_STATE_GOING) > > > remove_module_kprobe_blacklist(mod); > > > -- > > > 2.11.0 > > > > > > > > > -- > > Masami Hiramatsu <mhiramat@kernel.org> > > > -- > Masami Hiramatsu <mhiramat@kernel.org>
-- Yours, Muchun
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