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

Masami,

Can you review this patch, and also, should this go to -rc and stable?

-- Steve


On Tue, 24 Nov 2020 19:57:19 +0800
Wang ShaoBo <bobo.shaobowang@huawei.com> 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 calling register_kretprobe(), for giving a warning message and
> terminate registration process.
>
> Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
> ---
> kernel/kprobes.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 41fdbb7953c6..7f54a70136f3 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -2117,6 +2117,14 @@ int register_kretprobe(struct kretprobe *rp)
> }
> }
>
> + /*
> + * Return error if it's being re-registered,
> + * also give a warning message to the developer.
> + */
> + ret = check_kprobe_rereg(&rp->kp);
> + if (WARN_ON(ret))
> + return ret;
> +
> rp->kp.pre_handler = pre_handler_kretprobe;
> rp->kp.post_handler = NULL;
> rp->kp.fault_handler = NULL;



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