[PATCH] riscv/kprobe: reclaim insn_slot on kprobe unregistration

[Jisheng Zhang]

On Mon, May 23, 2022 at 09:51:24AM +0800, Liao Chang 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.

+ Guo Ren

Nice catch! I think csky needs the fix as well.

> 
> This bug reported by Chen Guokai <chenguokai17 at mails.ucas.ac.cn>.

This needs a "Reported-by: ..." tag

> 
> Signed-off-by: Liao Chang <liaochang1 at huawei.com>
> ---
>  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
> 
> 
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