Messages in this thread | | | Date | Tue, 15 Dec 2020 12:31:19 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] kretprobe: avoid re-registration of the same kretprobe earlier |
| |
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, > > > >
-- Masami Hiramatsu <mhiramat@kernel.org>
| |