On Thu, 24 Sep 2020 18:06:06 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> On Mon, 21 Sep 2020 14:25:19 +0200
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > The patch below does not apply to the 5.4-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@xxxxxxxxxxxxxxx>.
> >
> > thanks,
> >
> > greg k-h
> >
>
>
> The below should apply and work for 5.4 - 4.4.
>
> Masami, can you verify that I did this correctly. It appears to pass
> all the ftrace tests, at least all the ones that pass without the patch ;-)
Thanks Steve! I think we should keep using hlist_for_each_entry_rcu() unless
backporting commit 7e6a71d8e601 ("kprobes: Use non RCU traversal APIs on
kprobe_tables if possible") (and this commit involves another improvement.)
>From b2dafed7da5e4ee5e82fdfe309d69ca6e189ef0d Mon Sep 17 00:00:00 2001
From: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Date: Fri, 18 Sep 2020 21:20:21 -0700
Subject: [PATCH] kprobes: fix kill kprobe which has been marked as gone
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.
Fixes: e8386a0cb22f ("kprobes: support probing module __exit function")
Co-developed-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: "Naveen N . Rao" <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200822030055.32383-1-songmuchun@xxxxxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
kernel/kprobes.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index bbff4bccb885..5646f291eb70 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2088,6 +2088,9 @@ static void kill_kprobe(struct kprobe *p)
{
struct kprobe *kp;
+ if (WARN_ON_ONCE(kprobe_gone(p)))
+ return;
+
p->flags |= KPROBE_FLAG_GONE;
if (kprobe_aggrprobe(p)) {
/*
@@ -2270,7 +2273,10 @@ 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_rcu(p, head, hlist)
+ hlist_for_each_entry_rcu(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))) {
@@ -2287,6 +2293,7 @@ static int kprobes_module_callback(struct notifier_block *nb,
*/
kill_kprobe(p);
}
+ }
}
mutex_unlock(&kprobe_mutex);
return NOTIFY_DONE;
--
2.25.1
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
