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

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Date:   Wed, 25 May 2022 14:23:50 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Liao Chang <liaochang1@...wei.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Naveen Rao <naveen.n.rao@...ux.vnet.ibm.com>,
        jszhang@...nel.org, linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] riscv/kprobe: reclaim insn_slot on kprobe unregistration

On Wed, May 25, 2022 at 9:46 AM 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>
> ---
> 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;
> +       }
Thx reviewed-by: Guo Ren <guoren@...nel.org>

You also could give a fixup patch to csky, thx:

diff --git a/arch/csky/kernel/probes/kprobes.c
b/arch/csky/kernel/probes/kprobes.c
index 42920f25e73c..661da54b418f 100644
--- a/arch/csky/kernel/probes/kprobes.c
+++ b/arch/csky/kernel/probes/kprobes.c
@@ -124,6 +124,10 @@ 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)

>  }
>
>  static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
> --
> 2.17.1
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/