Messages in this thread | | | Date | Wed, 2 Dec 2020 08:32:53 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] kretprobe: avoid re-registration of the same kretprobe earlier |
| |
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>
| |