On Fri, 21 Aug 2020 21:28:43 +0900
Masami Hiramatsu <mhira...@kernel.org> wrote:
> Hi Muchun,
>
> On Thu, 20 Aug 2020 11:19:33 +0800
> Muchun Song <songmuc...@bytedance.com> wrote:
>
> > If a kprobe is marked as gone, we should not kill it again. Otherwise,
> > we can disarm the kprobe more than once. In that case, the statistics
> > of kprobe_ftrace_enabled can unbalance which can lead to that kprobe
> > do not work.
> >
>
> Good catch! Hmm, I think we also need an assertion in
> kill_kprobe() so that p is already gone. Anyway, this looks good to me.
>
> Acked-by: Masami Hiramatsu <mhira...@kernel.org>
>
> Thanks!
>
> > Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at
> > kprobe_ftrace_handler")
BTW, this fixes older bug than this commit.
Fixes: e8386a0cb22f ("kprobes: support probing module __exit function")
Thank you,
> > Signed-off-by: Muchun Song <songmuc...@bytedance.com>
> > Co-developed-by: Chengming Zhou <zhouchengm...@bytedance.com>
> > Signed-off-by: Chengming Zhou <zhouchengm...@bytedance.com>
> > ---
> > kernel/kprobes.c | 6 +++++-
> > 1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index d36e2b017588..7bac3ea44ff4 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -2422,7 +2422,10 @@ static int kprobes_module_callback(struct
> > notifier_block *nb,
> > mutex_lock(&kprobe_mutex);
> > for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
> > head = &kprobe_table[i];
> > - hlist_for_each_entry(p, head, hlist)
> > + hlist_for_each_entry(p, head, hlist) {
> > + if (kprobe_gone(p))
> > + continue;
> > +
> > if (within_module_init((unsigned long)p->addr, mod) ||
> > (checkcore &&
> > within_module_core((unsigned long)p->addr, mod))) {
> > @@ -2439,6 +2442,7 @@ static int kprobes_module_callback(struct
> > notifier_block *nb,
> > */
> > kill_kprobe(p);
> > }
> > + }
> > }
> > if (val == MODULE_STATE_GOING)
> > remove_module_kprobe_blacklist(mod);
> > --
> > 2.11.0
> >
>
>
> --
> Masami Hiramatsu <mhira...@kernel.org>
--
Masami Hiramatsu <mhira...@kernel.org>
