On Mon, 30 Nov 2020 16:18:50 -0500
Steven Rostedt <rost...@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.shaobow...@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.shaobow...@huawei.com>
> > Signed-off-by: Cheng Jian <cj.chengj...@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 <mhira...@kernel.org>
