linux-kernel - Re: [PATCH v2] riscv/kprobe: reclaim insn

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Message-Id: <20220527003330.68f1fc0f58ecec812a7d037e@kernel.org>
Date:   Fri, 27 May 2022 00:33:30 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Liao Chang <liaochang1@...wei.com>
Cc:     <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <aou@...s.berkeley.edu>, <rostedt@...dmis.org>,
        <peterz@...radead.org>, <naveen.n.rao@...ux.vnet.ibm.com>,
        <jszhang@...nel.org>, <guoren@...nel.org>,
        <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] riscv/kprobe: reclaim insn_slot on kprobe
 unregistration

On Wed, 25 May 2022 09:44:24 +0800
Liao Chang <liaochang1@...wei.com> wrote:

> On kprobe registration kernel allocate one insn_slot for new kprobe,
> but it forget to reclaim the insn_slot on unregistration, leading to a
> potential leakage.
> 
> Reported-by: Chen Guokai <chenguokai17@...ls.ucas.ac.cn>
> Signed-off-by: Liao Chang <liaochang1@...wei.com>

Looks good to me.

Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported")
Cc: stable@...r.kernel.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,


> ---
> v2:
>   Add Reported-by tag
> 
>  arch/riscv/kernel/probes/kprobes.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
> index e6e950b7cf32..f12eb1fbb52c 100644
> --- a/arch/riscv/kernel/probes/kprobes.c
> +++ b/arch/riscv/kernel/probes/kprobes.c
> @@ -110,6 +110,10 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
>  
>  void __kprobes arch_remove_kprobe(struct kprobe *p)
>  {
> +	if (p->ainsn.api.insn) {
> +		free_insn_slot(p->ainsn.api.insn, 0);
> +		p->ainsn.api.insn = NULL;
> +	}
>  }
>  
>  static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
> -- 
> 2.17.1
> 


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