kprobe: reverse kp->flags when arm_kprobe failed

[PATCH] kprobe: reverse kp->flags when arm_kprobe failed

Posted by Li Qiang 3 years, 7 months ago

In aggregate kprobe case, when arm_kprobe failed,
we need set the kp->flags with KPROBE_FLAG_DISABLED again.
If not, the 'kp' kprobe will been considered as enabled
but it actually not enabled.

Signed-off-by: Li Qiang <liq3ea@163.com>
---
 kernel/kprobes.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 08350e35a..333454df5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2424,8 +2424,11 @@ int enable_kprobe(struct kprobe *kp)
 	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
 		p->flags &= ~KPROBE_FLAG_DISABLED;
 		ret = arm_kprobe(p);
-		if (ret)
+		if (ret) {
 			p->flags |= KPROBE_FLAG_DISABLED;
+			if (p != kp)
+				kp->flags |= KPROBE_FLAG_DISABLED;
+		}
 	}
 out:
 	mutex_unlock(&kprobe_mutex);
-- 
2.25.1

Re: [PATCH] kprobe: reverse kp->flags when arm_kprobe failed

Posted by Li Qiang 3 years, 6 months ago

Hello all,

What's the status of this patch?

Li Qiang <liq3ea@163.com> 于2022年9月3日周六 00:00写道：
>
> In aggregate kprobe case, when arm_kprobe failed,
> we need set the kp->flags with KPROBE_FLAG_DISABLED again.
> If not, the 'kp' kprobe will been considered as enabled
> but it actually not enabled.
>
> Signed-off-by: Li Qiang <liq3ea@163.com>
> ---
>  kernel/kprobes.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 08350e35a..333454df5 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2424,8 +2424,11 @@ int enable_kprobe(struct kprobe *kp)
>         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
>                 p->flags &= ~KPROBE_FLAG_DISABLED;
>                 ret = arm_kprobe(p);
> -               if (ret)
> +               if (ret) {
>                         p->flags |= KPROBE_FLAG_DISABLED;
> +                       if (p != kp)
> +                               kp->flags |= KPROBE_FLAG_DISABLED;
> +               }
>         }
>  out:
>         mutex_unlock(&kprobe_mutex);
> --
> 2.25.1
>

Re: [PATCH] kprobe: reverse kp->flags when arm_kprobe failed

Posted by Masami Hiramatsu (Google) 3 years, 6 months ago

On Fri,  2 Sep 2022 08:58:20 -0700
Li Qiang <liq3ea@163.com> wrote:

> In aggregate kprobe case, when arm_kprobe failed,
> we need set the kp->flags with KPROBE_FLAG_DISABLED again.
> If not, the 'kp' kprobe will been considered as enabled
> but it actually not enabled.
> 
> Signed-off-by: Li Qiang <liq3ea@163.com>

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks!

> ---
>  kernel/kprobes.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 08350e35a..333454df5 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2424,8 +2424,11 @@ int enable_kprobe(struct kprobe *kp)
>  	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
>  		p->flags &= ~KPROBE_FLAG_DISABLED;
>  		ret = arm_kprobe(p);
> -		if (ret)
> +		if (ret) {
>  			p->flags |= KPROBE_FLAG_DISABLED;
> +			if (p != kp)
> +				kp->flags |= KPROBE_FLAG_DISABLED;
> +		}
>  	}
>  out:
>  	mutex_unlock(&kprobe_mutex);
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] kprobe: reverse kp->flags when arm_kprobe failed

Posted by Li Qiang 3 years, 6 months ago

Masami Hiramatsu <mhiramat@kernel.org> 于2022年9月9日周五 21:07写道：
>
> On Fri,  2 Sep 2022 08:58:20 -0700
> Li Qiang <liq3ea@163.com> wrote:
>
> > In aggregate kprobe case, when arm_kprobe failed,
> > we need set the kp->flags with KPROBE_FLAG_DISABLED again.
> > If not, the 'kp' kprobe will been considered as enabled
> > but it actually not enabled.
> >
> > Signed-off-by: Li Qiang <liq3ea@163.com>
>
> Looks good to me.
>
> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>


Hello Masami,

Who should merge this,  you? This issue will crash the kernel before:

0bc11ed5ab60c135aa764a62c02cd5ea68289de4 commit ("kprobes: Allow
kprobes coexist with
livepatch") and
8094029330a2f03fb406ecff80671cf27ce28d42 commit("libbpf: Cleanup the
legacy kprobe_event on failed add/attach_event()")

Thanks,
Li Qiang

>
> Thanks!
>
> > ---
> >  kernel/kprobes.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 08350e35a..333454df5 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -2424,8 +2424,11 @@ int enable_kprobe(struct kprobe *kp)
> >       if (!kprobes_all_disarmed && kprobe_disabled(p)) {
> >               p->flags &= ~KPROBE_FLAG_DISABLED;
> >               ret = arm_kprobe(p);
> > -             if (ret)
> > +             if (ret) {
> >                       p->flags |= KPROBE_FLAG_DISABLED;
> > +                     if (p != kp)
> > +                             kp->flags |= KPROBE_FLAG_DISABLED;
> > +             }
> >       }
> >  out:
> >       mutex_unlock(&kprobe_mutex);
> > --
> > 2.25.1
> >
>
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>

Re: [PATCH] kprobe: reverse kp->flags when arm_kprobe failed

Posted by Li Qiang 3 years, 7 months ago

Kindly ping.

Li Qiang <liq3ea@163.com> 于2022年9月3日周六 00:00写道：
>
> In aggregate kprobe case, when arm_kprobe failed,
> we need set the kp->flags with KPROBE_FLAG_DISABLED again.
> If not, the 'kp' kprobe will been considered as enabled
> but it actually not enabled.
>
> Signed-off-by: Li Qiang <liq3ea@163.com>
> ---
>  kernel/kprobes.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 08350e35a..333454df5 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2424,8 +2424,11 @@ int enable_kprobe(struct kprobe *kp)
>         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
>                 p->flags &= ~KPROBE_FLAG_DISABLED;
>                 ret = arm_kprobe(p);
> -               if (ret)
> +               if (ret) {
>                         p->flags |= KPROBE_FLAG_DISABLED;
> +                       if (p != kp)
> +                               kp->flags |= KPROBE_FLAG_DISABLED;
> +               }
>         }
>  out:
>         mutex_unlock(&kprobe_mutex);
> --
> 2.25.1
>