Messages in this thread | | | Subject | Re: [PATCH] kretprobe: avoid re-registration of the same kretprobe earlier | From | "Wangshaobo (bobo)" <> | Date | Tue, 15 Dec 2020 16:39:30 +0800 |
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Hi Masami,
I will update and resend it soon
Thank you
-- ShaoBo
在 2020/12/15 11:31, Masami Hiramatsu 写道: > Hi ShaoBo, > > On Wed, 2 Dec 2020 09:23:35 +0800 > "Wangshaobo (bobo)" <bobo.shaobowang@huawei.com> wrote: > >> Hi steve, Masami, >> >> Thanks for your works, i will check code again and modify properly >> according to steve's suggestion. >> > Can you update your patch and resend it? > > Thank you, > >> -- 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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