2021-01-28 12:45:38

by Wangshaobo (bobo)

Subject: [PATCH v2] kretprobe: avoid re-registration of the same kretprobe earlier

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.

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 running register_kretprobe()'s body, for giving a warning message
and terminate registration process.

Signed-off-by: Wang ShaoBo <[email protected]>
Signed-off-by: Cheng Jian <[email protected]>
---
kernel/kprobes.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f7fb5d135930..5c4a884953e9 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1978,6 +1978,10 @@ int register_kretprobe(struct kretprobe *rp)
if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset))
return -EINVAL;

+ /* If only rp->kp.addr is specified, check reregistering kprobes */
+ if (rp->kp.addr && check_kprobe_rereg(&rp->kp))
+ return -EINVAL;
+
if (kretprobe_blacklist_size) {
addr = kprobe_addr(&rp->kp);
if (IS_ERR(addr))
--
2.25.1

2021-01-28 18:13:01

by Steven Rostedt

Subject: Re: [PATCH v2] kretprobe: avoid re-registration of the same kretprobe earlier

Masami,

Care to review?

Thanks!

-- Steve


On Thu, 28 Jan 2021 20:44:27 +0800
Wang ShaoBo <[email protected]> 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.
>
> 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 running register_kretprobe()'s body, for giving a warning message
> and terminate registration process.
>
> Signed-off-by: Wang ShaoBo <[email protected]>
> Signed-off-by: Cheng Jian <[email protected]>
> ---
> kernel/kprobes.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index f7fb5d135930..5c4a884953e9 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1978,6 +1978,10 @@ int register_kretprobe(struct kretprobe *rp)
> if (!kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset))
> return -EINVAL;
>
> + /* If only rp->kp.addr is specified, check reregistering kprobes */
> + if (rp->kp.addr && check_kprobe_rereg(&rp->kp))
> + return -EINVAL;
> +
> if (kretprobe_blacklist_size) {
> addr = kprobe_addr(&rp->kp);
> if (IS_ERR(addr))

2021-01-29 16:33:38

by Steven Rostedt

Subject: Re: [PATCH v2] kretprobe: avoid re-registration of the same kretprobe earlier

On Fri, 29 Jan 2021 22:29:47 +0900
Masami Hiramatsu <[email protected]> wrote:

> I'll send a patch over this to replace those check with WARN_ON() since
> it's a software bug and should be fixed.

Please use WARN_ON_ONCE()

Thanks!

-- Steve

2021-01-29 16:33:54

by Steven Rostedt

Subject: Re: [PATCH v2] kretprobe: avoid re-registration of the same kretprobe earlier

On Fri, 29 Jan 2021 15:23:47 +0530
"Naveen N. Rao" <[email protected]> wrote:

> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index f7fb5d135930fa..63a36f33565354 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1530,6 +1530,7 @@ static inline int check_kprobe_rereg(struct kprobe *p)
> ret = -EINVAL;
> mutex_unlock(&kprobe_mutex);
>
> + WARN_ON(ret);
> return ret;
> }

Please use WARN_ON_ONCE(ret);

Thanks,

-- Steve