Messages in this thread | | | Subject | Re: [PATCH] kretprobe: avoid re-registration of the same kretprobe earlier | From | "Wangshaobo (bobo)" <> | Date | Wed, 2 Dec 2020 09:23:35 +0800 |
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Hi steve, Masami,
Thanks for your works, i will check code again and modify properly according to steve's suggestion.
-- ShaoBo
在 2020/12/2 7:32, Masami Hiramatsu 写道: > On Mon, 30 Nov 2020 16:18:50 -0500 > Steven Rostedt <rostedt@goodmis.org> wrote: > >> Masami, >> >> Can you review this patch, and also, should this go to -rc and stable? >> >> -- Steve > Thanks for ping me! > >> On Tue, 24 Nov 2020 19:57:19 +0800 >> Wang ShaoBo <bobo.shaobowang@huawei.com> wrote: >> >>> Our system encountered a re-init error when re-registering same kretprobe, >>> where the kretprobe_instance in rp->free_instances is illegally accessed >>> after re-init. > Ah, OK. Anyway if re-register happens on kretprobe, it must lose instances > on the list before checking re-register in register_kprobe(). > So the idea looks good to me. > > >>> Implementation to avoid re-registration has been introduced for kprobe >>> before, but lags for register_kretprobe(). We must check if kprobe has >>> been re-registered before re-initializing kretprobe, otherwise it will >>> destroy the data struct of kretprobe registered, which can lead to memory >>> leak, system crash, also some unexpected behaviors. >>> >>> we use check_kprobe_rereg() to check if kprobe has been re-registered >>> before calling register_kretprobe(), for giving a warning message and >>> terminate registration process. >>> >>> Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com> >>> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> >>> --- >>> kernel/kprobes.c | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>> diff --git a/kernel/kprobes.c b/kernel/kprobes.c >>> index 41fdbb7953c6..7f54a70136f3 100644 >>> --- a/kernel/kprobes.c >>> +++ b/kernel/kprobes.c >>> @@ -2117,6 +2117,14 @@ int register_kretprobe(struct kretprobe *rp) >>> } >>> } >>> >>> + /* >>> + * Return error if it's being re-registered, >>> + * also give a warning message to the developer. >>> + */ >>> + ret = check_kprobe_rereg(&rp->kp); >>> + if (WARN_ON(ret)) >>> + return ret; > If you call this here, you must make sure kprobe_addr() is called on rp->kp. > But if kretprobe_blacklist_size == 0, kprobe_addr() is not called before > this check. So it should be in between kprobe_on_func_entry() and > kretprobe_blacklist_size check, like this > > if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset)) > return -EINVAL; > > addr = kprobe_addr(&rp->kp); > if (IS_ERR(addr)) > return PTR_ERR(addr); > rp->kp.addr = addr; > > ret = check_kprobe_rereg(&rp->kp); > if (WARN_ON(ret)) > return ret; > > if (kretprobe_blacklist_size) { > for (i = 0; > > + ret = check_kprobe_rereg(&rp->kp); > > > Thank you, > >
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