* [PATCH] kprobes: Fix kill kprobe which has been marked as gone
@ 2020-08-20 3:19 Muchun Song
2020-08-21 12:28 ` Masami Hiramatsu
0 siblings, 1 reply; 4+ messages in thread
From: Muchun Song @ 2020-08-20 3:19 UTC (permalink / raw)
To: naveen.n.rao, anil.s.keshavamurthy, davem, mhiramat,
songliubraving
Cc: linux-kernel, Muchun Song, Chengming Zhou
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: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Chengming Zhou <zhouchengming@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
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] kprobes: Fix kill kprobe which has been marked as gone
2020-08-20 3:19 [PATCH] kprobes: Fix kill kprobe which has been marked as gone Muchun Song
@ 2020-08-21 12:28 ` Masami Hiramatsu
2020-08-21 13:28 ` Masami Hiramatsu
0 siblings, 1 reply; 4+ messages in thread
From: Masami Hiramatsu @ 2020-08-21 12:28 UTC (permalink / raw)
To: Muchun Song
Cc: naveen.n.rao, anil.s.keshavamurthy, davem, songliubraving,
linux-kernel, Chengming Zhou
Hi Muchun,
On Thu, 20 Aug 2020 11:19:33 +0800
Muchun Song <songmuchun@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 <mhiramat@kernel.org>
Thanks!
> Fixes: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler")
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
> Signed-off-by: Chengming Zhou <zhouchengming@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 <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] kprobes: Fix kill kprobe which has been marked as gone
2020-08-21 12:28 ` Masami Hiramatsu
@ 2020-08-21 13:28 ` Masami Hiramatsu
2020-08-22 2:31 ` [External] " Muchun Song
0 siblings, 1 reply; 4+ messages in thread
From: Masami Hiramatsu @ 2020-08-21 13:28 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Muchun Song, naveen.n.rao, anil.s.keshavamurthy, davem,
songliubraving, linux-kernel, Chengming Zhou
On Fri, 21 Aug 2020 21:28:43 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Hi Muchun,
>
> On Thu, 20 Aug 2020 11:19:33 +0800
> Muchun Song <songmuchun@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 <mhiramat@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 <songmuchun@bytedance.com>
> > Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
> > Signed-off-by: Chengming Zhou <zhouchengming@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 <mhiramat@kernel.org>
--
Masami Hiramatsu <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [External] Re: [PATCH] kprobes: Fix kill kprobe which has been marked as gone
2020-08-21 13:28 ` Masami Hiramatsu
@ 2020-08-22 2:31 ` Muchun Song
0 siblings, 0 replies; 4+ messages in thread
From: Muchun Song @ 2020-08-22 2:31 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: naveen.n.rao, anil.s.keshavamurthy, davem, songliubraving, LKML,
Chengming Zhou
On Fri, Aug 21, 2020 at 9:28 PM Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> On Fri, 21 Aug 2020 21:28:43 +0900
> Masami Hiramatsu <mhiramat@kernel.org> wrote:
>
> > Hi Muchun,
> >
> > On Thu, 20 Aug 2020 11:19:33 +0800
> > Muchun Song <songmuchun@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 <mhiramat@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")
Yeah, it's right. Thanks.
>
> Thank you,
>
> > > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> > > Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
> > > Signed-off-by: Chengming Zhou <zhouchengming@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 <mhiramat@kernel.org>
>
>
> --
> Masami Hiramatsu <mhiramat@kernel.org>
--
Yours,
Muchun
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-08-20 3:19 [PATCH] kprobes: Fix kill kprobe which has been marked as gone Muchun Song
2020-08-21 12:28 ` Masami Hiramatsu
2020-08-21 13:28 ` Masami Hiramatsu
2020-08-22 2:31 ` [External] " Muchun Song
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